Spinoza: Complete Works

[Known only from the O.P. The original is lost.]

With such reluctance did I recently tear myself away from your side when visiting you at your retreat in Rijnsburg, that no sooner am I back in England than I am endeavouring to join you again, as far as possible, at least by exchange of letters. Substantial learning, combined with humanity and courtesy—all of which nature and diligence have so amply bestowed on you—hold such an allurement as to gain the affection of any men of quality and of liberal education. Come then, most excellent Sir, let us join hands in unfeigned friendship, and let us assiduously cultivate that friendship with devotion and service of every kind. Whatever my poor resources can furnish, consider as yours. As to the gifts of mind that you possess, let me claim a share in them, as this cannot impoverish you.

At Rijnsburg we conversed about God, about infinite Extension and Thought, about the difference and agreement of these attributes, and about the nature of the union of the human soul with the body; and also about the principles of the Cartesian and Baconian philosophy. But since we then spoke about such important topics as through a lattice-window and only in a cursory way, and in the meantime all these things continue to torment me, let me now, by the right of the friendship entered upon between us, engage in a discussion with you and cordially beg you to set forth at somewhat greater length your views on the above-mentioned subjects. In particular, please be good enough to enlighten me on these two points: first, wherein you place the true distinction between Extension and Thought, and second, what defects you find in the philosophy of Descartes and Bacon, and how you consider that these can be removed and replaced by sounder views. The more frankly you write to me on these and similar subjects, the more closely you will bind me to you and place me under a strong obligation to make an equal return, if only I can.

Here there are already in the press Certain Physiological Essays,¹ written by an English nobleman, a man of extraordinary learning. These treat of the nature of air and its elastic property, as proved by forty-three experiments; and also of fluidity and firmness and the like. As soon as they are printed, I shall see to it that they are delivered to you through a friend who happens to be crossing the sea. Meanwhile, farewell, and remember your friend, who is,

LETTER 2
To the most noble and learned H. Oldenburg, from B.d.S.

[Known only from the O.P. The original is lost. No date is given, but a conjectural date is September 1661.]

You yourself will be able to judge what pleasure your friendship affords me, if only your modesty will allow you to consider the estimable qualities with which you are richly endowed. And although, with these qualities in mind, I feel myself not a little presumptuous in venturing upon this relationship, especially when I reflect that between friends all things, and particularly things of the spirit, should be shared, nevertheless this step is to be accredited not so much to me as to your courtesy, and also your kindness. From your great courtesy you have been pleased to belittle yourself, and from your abundant kindness so to enlarge me, that I do not hesitate to enter upon the friendship which you firmly extend to me and deign to ask of me in return, a friendship which it shall be my earnest endeavour diligently to foster.

As for my mental endowments, such as they are, I would most willingly have you make claim on them even if I knew that this would be greatly to my detriment. But lest I seem in this way to want to refuse you what you ask by right of friendship, I shall attempt to explain my views on the subjects we spoke of—although I do not think that this will be the means of binding you more closely to me unless I have your kind indulgence.

I shall begin therefore with a brief discussion of God, whom I define as a Being consisting of infinite attributes, each of which is infinite or supremely perfect in its own kind.² Here it should be observed that by attribute I mean every thing that is conceived in itself and through itself, so that its conception does not involve the conception of any other thing. For example, extension is conceived through itself and in itself, but not so motion; for the latter is conceived in something else, and its conception involves extension.³

That this is a true definition of God is evident from the fact that by God we understand a supremely perfect and absolutely infinite Being. The existence of such a Being is easily proved from this definition; but as this is not the place for such a proof,⁴ I shall pass it over. The points I need to prove here in order to satisfy your first enquiry, esteemed Sir, are as follows: first, that in Nature there cannot exist two substances without their differing entirely in essence; secondly, that a substance cannot be produced, but that it is of its essence to exist; third, every substance must be infinite, or supremely perfect in its kind.⁵

With these points established, esteemed Sir, provided that at the same time you attend to the definition of God, you will readily perceive the direction of my thoughts, so that I need not be more explicit on this subject. However, in order to provide a clear and concise proof, I can think of no better expedient than to arrange them in geometrical style and to submit them to the bar of your judgment. I therefore enclose them separately herewith⁶ and await your verdict on them.

Secondly, you ask me what errors I see in the philosophy of Descartes and Bacon. In this request, too, I shall try to oblige you, although it is not my custom to expose the errors of others. The first and most important error is this, that they have gone far astray from knowledge of the first cause and origin of all things. Secondly, they have failed to understand the true nature of the human mind. Thirdly, they have never grasped the true cause of error. Only those who are completely destitute of all learning and scholarship can fail to see the critical importance of true knowledge of these three points.

That they have gone far astray from true knowledge of the first cause and of the human mind can readily be gathered from the truth of the three propositions to which I have already referred; so I confine myself to point out the third error. Of Bacon I shall say little; he speaks very confusedly on this subject, and simply makes assertions while proving hardly anything. In the first place he takes for granted that the human intellect, besides the fallibility of the senses, is by its very nature liable to error, and fashions everything after the analogy of its own nature, and not after the analogy of the universe, so that it is like a mirror presenting an irregular surface to the rays it receives, mingling its own nature with the nature of reality, and so forth.⁷ Secondly, he holds that the human intellect, by reason of its peculiar nature, is prone to abstractions,⁸ and imagines as stable things that are in flux, and so on. Thirdly, he holds that the human intellect is in constant activity, and cannot come to a halt or rest.⁹ Whatever other causes he assigns can all be readily reduced to the one Cartesian principle, that the human will is free and more extensive than the intellect, or, as Verulam more confusedly puts it, the intellect is not characterised as a dry light, but receives infusion from the will.¹⁰ (We should here observe that Verulam often takes intellect for mind, therein differing from Descartes.) This cause, then, disregarding the others as being of little importance, I shall show to be false. Indeed, they would easily have seen this for themselves, had they but given consideration to the fact that the will differs from this or that volition in the same way as whiteness differs from this or that white object, or as humanity differs from this or that human being. So to conceive the will to be the cause of this or that volition is as impossible as to conceive humanity to be the cause of Peter and Paul.¹¹

Since, then, the will is nothing more than a mental construction (ens rationis), it can in no way be said to be the cause of this or that volition. Particular volitions, since they need a cause to exist, cannot be said to be free; rather, they are necessarily determined to be such as they are by their own causes. Finally, according to Descartes, errors are themselves particular volitions, from which it necessarily follows that errors—that is, particular volitions—are not free, but are determined by external causes and in no way by the will. This is what I undertook to demonstrate. Etc.

LETTER 3
To the esteemed B.d.S., from Henry Oldenburg

[Known only from the O.P. The original is lost.]

Your very learned letter has been delivered to me and read with great pleasure. I warmly approve your geometrical style of proof, but at the same time I blame my obtuseness for not so readily grasping what you with such exactitude teach. So I beg you to allow me to present the evidence of this sluggishness of mine by putting the following questions and seeking from you their solutions.

The first is, do you understand clearly and indubitably that, solely from the definition of God which you give, it is demonstrated that such a Being exists? For my part, when I reflect that definitions contain no more than conceptions of our mind, and that our mind conceives many things that do not exist and is most prolific in multiplying and augmenting things once conceived, I do not yet see how I can infer the existence of God from the conception I have of him. Indeed, from a mental accumulation of all the perfections I discover in men, animals, vegetables, minerals and so on, I can conceive and form one single substance which possesses in full all those qualities; even more, my mind is capable of multiplying and augmenting them to infinity, and so of fashioning for itself a most perfect and excellent Being. Yet the existence of such a Being can by no means be inferred from this.

My second questions is, are you quite certain that Body is not limited by Thought, nor Thought by Body? For it is still a matter of controversy as to what Thought is, whether it is a corporeal motion or a spiritual activity quite distinct from what is corporeal.

My third question is, do you regard those axioms you have imparted to me as being indemonstrable principles, known by the light of Nature and standing in no need of proof? It may be that the first axiom is that of kind, but I do not see how the other three can be accounted as such. For the second axiom supposes that there exists in Nature nothing but substance and accidents, whereas many maintain that time and place are in neither category. Your third axiom, that ‘things having different attributes have nothing in common’ is so far from being clearly conceived by me that the entire Universe seems rather to prove the contrary. All things known to us both differ from one another in some respects and agree in other respects. Finally, your fourth axiom, namely, ‘things which have nothing in common with one another cannot be the cause one of the other’, is not so clear to my befogged intellect as not to require some light to be shed on it. For God has nothing formally in common with created things; yet we almost all hold him to be their cause.

Since, then, these axioms do not seem to me to be placed beyond all hazard of doubt, you may readily conjecture that your propositions based on them are bound to be shaky. And the more I consider them, the more I am overwhelmed with doubt concerning them. Against the first I hold that two men are two substances and of the same attribute, since they are both capable of reasoning; and thence I conclude that there are two substances of the same attribute. With regard to the second I consider that, since nothing can be the cause of itself, we can scarcely understand how it can be true that ‘Substance cannot be produced, nor can it be produced by any other substance.’ For this proposition asserts that all substances are causes of themselves, that they are each and all independent of one another, and it makes them so many Gods, in this way denying the first cause of all things.

This I willingly confess I cannot grasp, unless you do me the kindness of disclosing to me somewhat more simply and more fully your opinion regarding this high matter, explaining what is the origin and production of substances, the interdependence of things and their subordinate relationships. I entreat you, by the friendship on which we have embarked, to deal with me frankly and confidently in this, and I urge you most earnestly to be fully convinced that all these things which you see fit to impart to me will be inviolate and secure, and that I shall in no way permit any of them to become public to your detriment or injury.

In our Philosophical Society we are engaged in making experiments and observations as energetically as our abilities allow, and we are occupied in composing a History of the Mechanical Arts, being convinced that the forms and qualities of things can best be explained by the principles of mechanics, that all Nature’s effects are produced by motion, figure, texture and their various combinations, and that there is no need to have recourse to inexplicable forms and occult qualities, the refuge of ignorance.

I shall send you the book I promised as soon as your Dutch ambassadors stationed here dispatch a messenger to the Hague (as they often do), or as soon as some other friend, to whom I can safely entrust it, goes your way.

Please excuse my prolixity and frankness, and I particularly urge you to take in good part, as friends do, what I have said frankly and without any disguise or courtly refinement, in replying to your letter. And believe me to be, sincerely and simply,

LETTER 4

[Known only from the O.P. The original is lost. No date is given, but a conjectural date is October 1661.]

While preparing to go to Amsterdam to spend a week or two there, I received your very welcome letter and read your objections to the three propositions which I sent you. On these alone I shall try to satisfy you, omitting the other matters for want of time.

To your first objection, then, I say that it is not from the definition of any thing whatsoever that the existence of the defined thing follows, but only (as I demonstrated in the Scholium which I attached to the three propositions) from the definition or idea of some attribute; that is (as I explained clearly in the case of the definition of God), from the definition of a thing which is conceived through itself and in itself. The ground for this distinction I have also stated in the aforementioned Scholium with sufficient clarity, I think, especially for a philosopher. A philosopher is supposed to know what is the difference between fiction and a clear and distinct conception, and also to know the truth of this axiom, to wit, that every definition, or clear and distinct idea, is true. Once these points are noted, I do not see what more is required in answer to the first question.

I therefore pass on to the solution of the second question. Here you seem to grant that, if Thought does not pertain to the nature of Extension, then Extension will not be limited by Thought; for surely it is only the example which causes you some doubt. But I beg you to note, if someone says that Extension is not limited by Extension, but by Thought, will he not also be saying that Extension is not infinite in an absolute sense, but only insofar as it is Extension? That is, does he not grant me that Extension is infinite not in an absolute sense, but only insofar as it is Extension, that is, infinite in its own kind?¹²

But, you say, perhaps Thought is a corporeal activity. Let it be so, although I do not concede it; but this one thing you will not deny, that Extension, insofar as it is Extension, is not Thought; and this suffices to explain my definition and to demonstrate the third proposition.

The third objection which you proceed to raise against what I have set down is this, that the axioms should not be accounted as ‘common notions’ (notiones communes).¹³ This is not the point I am urging; but you also doubt their truth, and you even appear to seek to prove that their contrary is more probable. But please attend to my definition of substance and accident,¹⁴ from which all these conclusions follow. For by substance I understand that which is conceived through itself and in itself, that is, that whose conception does not involve the conception of another thing; and by modification or accident I understand that which is in something else and is conceived through that in which it is. Hence it is clearly established, first, that substance is prior in nature to its accidents; for without it these can neither exist nor be conceived. Secondly, besides substance and accidents nothing exists in reality, or externally to the intellect; for whatever there is, is conceived either through itself or through something else, and its conception either does or does not involve the conception of another thing. Thirdly, things which have different attributes have nothing in common with one another;¹⁵ for I have explained an attribute as that whose conception does not involve the conception of another thing. Fourth and last, of things which have nothing in common with one another, one cannot be the cause of another; for since in the effect there would be nothing in common with the cause, all it would have, it would have from nothing.

As for your contention that God has nothing formally in common with created things, etc., I have maintained the exact opposite in my definition. For I said that God is a Being consisting of infinite attributes, each of which is infinite, or supremely perfect, in its kind.

As to your objection to my first proposition, I beg you, my friend, to consider that men are not created, but only begotten, and that their bodies already existed, but in a different form.¹⁶ However, the conclusion is this, as I am quite willing to admit, that if one part of matter were to be annihilated, the whole of Extension would also vanish at the same time.

The second proposition does not make many gods, but one only, to wit, a God consisting of infinite attributes, etc.

LETTER 5
To the esteemed B.d.S., from Henry Oldenburg

[Known only from the O.P. The original is lost.]

Receive herewith the little book¹⁷ I promised, and send me in return your opinion of it, especially with regard to the experiments he concludes concerning nitre, fluidity and solidity. I am most grateful to you for your learned second letter, which I received yesterday. Still, I very much regret that your journey to Amsterdam prevented you from answering all my doubts. I beg you to send me, as soon as your leisure permits, what was then omitted. Your last letter did indeed shed a great deal of light for me, but not so much as to dispel all the darkness. This will, I hope, be the happy outcome when you will have clearly and distinctly furnished me with your views on the true and primary origin of things. For as long as it is not quite clear to me from what cause and in what manner things began to be, and by what connection they depend on the first cause, if there be such a thing, then all that I hear and all that I read seems to me quite incoherent. I therefore most earnestly beg you, most learned Sir, to light my way in this matter, and not to doubt my good faith and gratitude. I am,

LETTER 6
To the most noble and learned Henry Oldenburg, from B.d.S. containing comments on the book of the most noble Robert Boyle, on Nitre, Fluidity and Solidity

[Printed in the O.P. The original is extant. The last two paragraphs of this translation appear only in the original. The letter is undated, but a conjectural date is early 1662.]

I have received the very talented Mr. Boyle’s book, and read it through, as far as time permitted. I thank you very much for this gift. I see that I was not wrong in conjecturing, when you first promised me this book, that you would not concern yourself with anything less than a matter of great importance. Meanwhile, learned Sir, you wish me to send you my humble opinion on what he has written. This I shall do, as far as my slender ability allows, noting those points which seem to me obscure or insufficiently demonstrated; but I have not as yet been able to peruse it all, far less examine it, because of my other commitments. Here, then, is that I find worthy of comment regarding Nitre, etc.

First, he gathers from his experiment on the redintegration of Nitre that Nitre is a heterogeneous thing, consisting of fixed and volatile parts. Its nature, however (at least as shown by its behaviour), is quite different from the nature of its component parts, although it arises from nothing but a mixture of these parts. For this conclusion to be regarded as valid, I suggest that a further experiment seems to be required to show that Spirit of Nitre is not really Nitre, and cannot be reduced to solid state or crystallised without the help of salt of lye. Or at least one ought to have enquired whether the quantity of fixed salt remaining in the crucible is always found to be the same from the same quantity of Nitre, and to vary proportionately with the quantity of Nitre. And as to what the esteemed author says (section 9) he discovered with the aid of scales, and the fact that the observed behaviour of Spirit of Nitre is so different from, and even sometimes contrary to, that of Nitre itself, in my view this does nothing to confirm his conclusion.

To make this clear, I shall briefly set forth what occurs to me as the simplest explanation of this redintegration of Nitre, and at the same time I shall add two or three quite easy experiments by which this explanation is to some extent confirmed. To explain what takes place as simply as possible, I shall posit no difference between Spirit of Nitre and Nitre itself other than that which is sufficiently obvious; to wit, that the particles of the latter are at rest whereas those of the former, when stirred, are in a state of considerable commotion. With regard to the fixed salt, I shall suppose that this in no way contributes to constituting the essence of Nitre. I shall consider it as the dregs of Nitre, from which the Spirit of Nitre (as I find) is itself not free; for they float in it in some abundance, although in a very powdery form. This salt, or these dregs, have pores or passages hollowed out to the size of the particles of Nitre. But when the Nitre particles were driven out of them by the action of fire, some of the passages became narrower and consequently others were forced to dilate, and the substance or walls of these passages became stiff and at the same time very brittle. So when Spirit of Nitre was dropped thereon, some of its particles began to force their way through those narrower passages; and since the particles are of unequal thickness (as Descartes has aptly demonstrated),¹⁸ they first bent the rigid walls of the passages like a bow, and then broke them. When they broke them, they forced those fragments to recoil, and, retaining the motion they already had, they remained as equally incapable as before of solidifying and crystallising. The parts of Nitre which made their way through the wider passages, since they did not touch the walls of those passages, were necessarily surrounded by some very fine matter and by this were driven upwards, in the same way as bits of wood by flame or heat, and were given off as smoke. But if they were sufficiently numerous, or if they united with fragments of the walls and with particles making their way through the narrower passages, they formed droplets flying upwards. But if the fixed salt is loosened by means of water¹⁹ or air and is rendered less active, then it becomes sufficiently capable of stemming the onrush of the particles of Nitre and of compelling them to lose the motion they possessed and to come again to a halt, just as does a cannonball when it strikes sand or mud. The redintegration of Nitre consists solely in this coagulation of the particles of Spirit of Nitre, and to bring this about the fixed salt acts as an instrument, as is clear from this explanation. So much for the redintegration.

Now, if you please, let us see first of all why Spirit of Nitre and Nitre itself differ so much in taste; secondly, why Nitre is inflammable, while spirit of Nitre is by no means so. To understand the first question, it should be noted that bodies in motion never come into contact with other bodies along their broadest surfaces, whereas bodies at rest lie on other bodies along their broadest surfaces. So particles of Nitre, if placed on the tongue while they are at rest, will lie on it along their broadest surfaces and will thus obstruct its pores, which is the cause of the cold sensation. Furthermore, the Nitre cannot be dissolved by saliva into such very minute particles. But if the particles are placed on the tongue while they are in active motion, they will come into contact with it by their more pointed surfaces and will make their way through its pores. And the more active their motion, the more sharply they will prick the tongue, just as a needle, as it either strikes the tongue with its point or lies lengthwise along the tongue, will cause different sensations to arise.

The reason why Nitre is inflammable and the Spirit of Nitre not so is this, that when particles of Nitre are at rest, they cannot so readily be borne upwards by fire as when they have their own motion in all directions. So when they are at rest, they resist the fire until such time as the fire separates them from one another and encompasses them from all sides. When it does encompass them, it carries them with it this way and that until they acquire a motion of their own and go up in smoke. But the particles of the Spirit of Nitre, being already in motion and separate from one another, are dilated in every direction in increased volume by a little heat of the fire; and thus some go up in smoke while others penetrate the matter supplying the fire before they can be completely encompassed by flame, and so they extinguish the fire rather than feed it.

I shall now pass on to experiments which seem to confirm this explanation. First, I found that the particles of Nitre which go up in smoke with a crackling noise are pure Nitre. For when I melted the Nitre again and again until the crucible became white-hot, and I kindled it with a live coal,²⁰ I collected its smoke in a cold glass flask until the flask was moistened thereby, and after that I moistened the flask yet further by breathing on it, and finally set it out to dry in the cold air.²¹ Thereupon little icicles²² of Nitre appeared here and there in the flask. Now it might be thought that this did not result solely from the volatile particles, but that the flame could be carrying with it whole particles of Nitre (to adopt the view of the esteemed author) and was driving out the fixed particles, along with the volatile, before they were dissolved. To remove such a possibility, I caused the smoke to ascend through a tube (A) over a foot long, as through a chimney, so that the heavier particles adhered to the tube, and I collected only the more volatile parts as they passed through the narrower aperture (B). The result was as I have said.

Even so, I did not stop at this point, but, as a further test, I took a larger quantity of Nitre, melted it, ignited it with a live coal and, as before, placed the tube (A) over the crucible; and as long as the flame lasted, I held a piece of mirror close to the aperture (B). To this some matter adhered which, on being exposed to air, became liquid. Although I waited some days, I could not observe any sign of Nitre; but when I added Spirit of Nitre to it, it turned into Nitre.

From this I think I can infer, first, that in the process of melting the fixed parts are separated from the volatile and that the flame drives them upwards separately from one another; secondly, that after the fixed parts are separated from the volatile with a crackling noise, they can never be reunited. From this we can infer, thirdly, that the parts which adhered to the flask and coalesced into little icicles were not the fixed parts, but only the volatile.

The second experiment, and one which seems to prove that the fixed parts are nothing but the dregs of Nitre, is as follows. I find that the more the Nitre is purified of its dregs, the more volatile it is, and the more apt to crystallise. For when I put crystals of purified or filtered Nitre in a glass goblet, such as A, and poured in a little cold water, it partly evaporated along with the cold water, and the particles escaping upwards stuck to the rim of the glass and coalesced into little icicles.

The third experiment, which seems to show that when the particles of Nitre lose their motion they become inflammable, is as follows. I trickled droplets of Spirit of Nitre into a damp paper bag and then added sand, between whose grains the Spirit of Nitre kept penetrating; and when the sand had absorbed all, or nearly all, the Spirit of Nitre, I dried it thoroughly in the same bag over a fire. Thereupon I removed the sand and set the paper against a live coal. As soon as it caught fire it gave off sparks, just as it usually does when it has absorbed Nitre itself.

If I had had time for further experimentation, I might have added other experiments which would perhaps make the matter quite clear. But as I am very much occupied with other matters, you will forgive me if I defer it for another time and proceed to other comments.

Section 5. When the esteemed author discusses incidentally the shape of particles of Nitre, he criticises modern writers as having wrongly represented it. I am not sure whether he includes Descartes; if so, he is perhaps criticising Descartes from what others have said. For Descartes is not speaking of particles visible to the eye. And I do not think that the esteemed author means that if icicles of Nitre were to be rubbed down until they became parallelepipeds or some other shape, they would cease to be Nitre. But perhaps he is referring to some chemists who admit nothing but what they can see with their eyes and touch with their hands.

Section 9. If this experiment could be carried out rigorously, it would completely confirm the conclusion I sought to draw from the first experiment mentioned above.

From section 13 to 18 the esteemed author tries to prove that all tangible qualities depend solely on motion, shape and other mechanical states. Since these demonstrations are not advanced by the esteemed author as being of a mathematical kind, there is no need to consider whether they carry complete conviction. Still, I do not know why the esteemed author strives so earnestly to draw this conclusion from this experiment of his, since it has already been abundantly proved by Verulam, and later by Descartes. Nor do I see that this experiment provides us with clearer evidence than other experiments readily available. For as far as heat is concerned, is not the same conclusion equally clear from the fact that if two pieces of wood, however cold they are, are rubbed against each other, they produce a flame simply as a result of that motion? Or that lime, sprinkled with water, becomes hot? As far as sound is concerned, I do not see what is to be found in this experiment more remarkable than is found in the boiling of ordinary water, and in many other instances. As to colour, to confine myself to the obvious, I need say no more than that we see green vegetation assuming so many and such varied colours. Again, bodies that give forth a foul smell emit even a fouler smell when agitated, and especially if they become somewhat warm. Finally sweet wine turns sour, and so with many other things. All these things, therefore, I would consider superfluous, if I may use the frankness of a philosopher. This I say because I fear that others, whose regard for the esteemed author is not as great as it should be, may misjudge him.²³

Section 24. I have already spoken of the cause of this phenomenon. Here I will merely add that I, too, have found by experience that particles of the fixed salt float in those saline drops. For when they flew upwards, they met a plate of glass which I had ready for the purpose. This I warmed somewhat so that any volatile matter should fly off, whereupon I observed some thick whitish matter adhering to the glass in places.

Section 25. In this section the esteemed author seems to intend to prove that the alkaline parts are driven hither and thither by the impact of the salt particles, whereas the salt particles ascend into the air by their own force. In explaining the phenomenon I too have said that the particles of Spirit of Nitre acquire a more lively motion because, on entering the wider passages, they must necessarily be encompassed by some very fine matter, and are thereby driven upwards as are particles of wood by fire, whereas the alkaline particles received their motion from the impact of particles of Spirit of Nitre penetrating through the narrower passages. Here I would add that pure water cannot so readily dissolve and soften the fixed parts. So it is not surprising that when Spirit of Nitre is poured onto the solution of the said fixed salt dissolved in water, an effervescence should take place such as the esteemed author describes in section 24. Indeed, I think this effervescence will be more violent than if Spirit of Nitre were to be added to the fixed salt while it is still intact. For in water it is dissolved into very minute molecules which can be more readily separated and more freely moved than when all the parts of the salt lie on one another and are firmly attached.

Section 26. Of the taste of the acidic Spirit I have already spoken, and so it remains only to speak of the alkali. When I placed this on the tongue, I felt a sensation of heat, followed by a prickling. This indicates to me that it is some kind of lime; for in just the same way that lime becomes heated with the aid of water, so does this salt with the aid of saliva, perspiration, Spirit of Nitre, and perhaps even moist air.

Section 27. It does not immediately follow that a particle of matter acquires a new shape by being joined to another; it only follows that it becomes larger, and this suffices to bring about the effect which is the object of the esteemed author’s inquiry in this section.

Section 33. What I think of the esteemed author’s method of philosophising I shall say when I have seen the Dissertation which is mentioned here and in the Introductory Essay, page 33.²⁴

Section 1. “It is quite manifest that they are to be reckoned among the most general states … etc.” In my view, notions which derive from popular usage, or which explicate Nature not as it is in itself but as it is related to human senses, should certainly not be regarded as concepts of the highest generality, nor should they be mixed (not to say confused) with notions that are pure and which explicate Nature as it is in itself. Of the latter kind are motion, rest, and their laws; of the former kind are visible, invisible, hot, cold, and, to say it at once, also fluid, solid, etc.

Section 5. “The first is the littleness of the bodies that compose it, for in the larger bodies … etc.” Even though bodies are small, they have (or can have) surfaces that are uneven and rough. So if large bodies move in such a way that the ratio of their motion to their mass is that of minute bodies to their particular mass, then they too would have to be termed fluid, if the word ‘fluid’ did not signify something extrinsic and were not merely adapted from common usage to mean those moving bodies whose minuteness and intervening spaces escape detection by human senses. So to divide bodies into fluid and solid would be the same as to divide them into visible and invisible.

The same section. “If we were not able to confirm it by chemical experiments.” One can never confirm it by chemical or any other experiments, but only by demonstration and by calculating. For it is by reason and calculation that we divide bodies to infinity, and consequently also the forces required to move them. We can never confirm this by experiments.

Section 6. “… great bodies are not well adapted to forming fluid bodies … etc.” Whether or not one understands by ‘fluid’ what I have just said, the thing is self-evident. But I do not see how the esteemed author confirms this by the experiments quoted in this section. For (since we want to doubt what is certain)²⁵ although bones may be unsuitable for forming chyle and similar fluids, perhaps they will be quite well adapted for forming some new kind of fluid.

Section 10. “… and this by making them less pliant than formerly … etc.” They could have coagulated into another body more solid than oil without any change in the parts, but merely because the parts driven into the receiver were separated from the rest. For bodies are lighter or heavier according to the kinds of fluids in which they are immersed. Thus particles of butter, when floating in milk, form part of the liquid; but when the milk is stirred and so acquires a new motion to which all the parts composing the milk cannot equally accommodate themselves, this in itself brings it about that some parts become heavier and force the lighter parts to the surface. But because these lighter parts are heavier than air so that they cannot compose a liquid with it, they are forced downwards by it; and because they are ill adapted for motion, they also cannot compose a liquid by themselves, but lie on one another and stick together. Vapours, too, when they are separated from the air, turn into water, which, in relation to air, may be termed a solid.

Section 13. “And I take as an example a bladder distended with water rather than one full of air … etc.” Since particles of water are always moving ceaselessly in all directions, it is clear that, if they are not restrained by surrounding bodies, the water will spread in all directions. Moreover, I am as yet unable to see how the distention of a bladder full of water helps to confirm his view about the small spaces. The reason why the particles of water do not yield when the sides of the bladder are pressed with a finger—as they otherwise would do if they were free—is this, that there is no equilibrium or circulation as there is when some body, say our finger, is surrounded by a fluid or water. But however much the water is pressed by the bladder, yet its particles will yield to a stone also enclosed in the bladder, in the same way as they usually do outside the bladder.

Same section. “whether there is any portion of matter….” We must maintain the affirmative, unless we prefer to look for a progression to infinity, or to grant that there is a vacuum, than which nothing can be more absurd.

Section 19. “… that the particles of the liquid find admittance into those pores and are held there (by which means … etc.)” This is not to be affirmed absolutely of all liquids which find admittance into the pores of other bodies. If the particles of Spirit of Nitre enter the pores of white paper, they make it stiff and friable. This may be seen if one pours a few drops into a small iron receptacle (A) which is at white heat and the smoke is channelled through a paper covering (B). Moreover, Spirit of Nitre softens leather, but does not make it moist; on the contrary, it shrinks it, as also does fire.

Same section. “Since Nature has designed them both for flying and for swimming….” He seeks the cause from purpose.

Section 23. “… though their motion is rarely perceived by us. Take then … etc.” Without this experiment and without going to any trouble, the thing is sufficiently evident from the fact that our breath, which in winter is obviously seen to be in motion, nevertheless cannot be seen so in summer, or in a heated room. Furthermore, if in summer the breeze suddenly cools, the vapours rising from water, since by reason of the change in the density of the air they cannot disperse through it as readily as they did before it cooled, gather again over the surface of the water in such quantity that they can easily be seen by us. Again, movement is often too gradual to be observed by us, as we can gather in the case of a sundial and the shadow cast by the sun; and it is frequently too swift to be observed by us, as can be seen in the case of an ignited piece of tinder when it is moved in a circle at some speed; for then we imagine the ignited part to be at rest at all points of the circle which it describes in its motion. I would here give the reasons for this, did I not judge it superfluous. Finally, let me say in passing that, to understand the nature of fluid in general, it is sufficient to know that we can move our hand in any direction without any resistance, the motion being proportionate to the fluid. This is quite obvious to those who give sufficient attention to those notions that explain Nature as it is in itself, not as it is related to human senses. Not that I therefore dismiss this piece of research as pointless. On the contrary, if in the case of every liquid such research were done with the greatest possible accuracy and reliability, I would consider it most useful for understanding their individual differences, a result much to be desired by all philosophers as being very necessary.

Section 7. “… (it seems consonant) to the universal laws of Nature….” This is Descartes’ demonstration, and I do not see that the esteemed author produces any original demonstration deriving from his experiments or observations.

I had made many notes here and in what follows, but later I saw that the esteemed author had corrected himself.

Section 15. “… and once four hundred and thirty-two (ounces) …”²⁶ If one compares it with the weight of quicksilver enclosed in the tube, it comes very near to the true weight. But I would consider it worthwhile to examine this, so as to obtain, as far as possible, the ratio between the lateral or horizontal pressure of air and the perpendicular pressure. I think it can be done in this way:

Let CD in figure 1 be a flat mirror thoroughly smoothed, and AB two pieces of marble directly touching each other. Let the marble piece A be attached to a hook E, and B to a cord N. T is a pulley, and G a weight which will show the force required to pull marble B away from marble A in a horizontal direction.

In figure 2, let F be a sufficiently strong silk thread by which marble B is attached to the floor, D a pulley, G a weight which will show the force required to pull marble A from marble B in a perpendicular direction.²⁷ It is not necessary to go into this at greater length.

Here you have, my good friend, what I have so far found worthy of note in regard to Mr. Boyle’s experiments. As to your first queries, when I look through my replies to them I do not see that I have omitted anything. And if perchance I have put something obscurely (as I often do through lack of vocabulary), please be good enough to point it out to me. I shall take pains to explain it more clearly.

As to the new question you raise, to wit, how things began to be and by what bond they depend on the first cause, I have written a complete short work on this subject, and also on the emendation of the intellect,²⁸ and I am engaged in transcribing and correcting it. But sometimes I put the work aside, because I do not as yet have any definite plan for its publication. I am naturally afraid that the theologians of our time may take offence, and, with their customary spleen, may attack me, who utterly dread brawling. I shall look for your advice in this matter, and, to let you know the contents of this work of mine which may ruffle the preachers, I tell you that many attributes which are attributed to God by them and by all whom I know of, I regard as belonging to creation. Conversely, other attributes which they, because of their prejudices, consider to belong to creation, I contend are attributes of God which they have failed to understand. Again, I do not differentiate between God and Nature in the way all those known to me have done. I therefore look to your advice, for I regard you as a most loyal friend whose good faith it would be wrong to doubt. Meanwhile, farewell, and, as you have begun, so continue to love me, who am,

LETTER 7
To the esteemed B.d.S., from Henry Oldenburg

[Known only from the O.P. The original is lost. The letter is undated, but a conjectural date is late in July 1662.]

It is many weeks ago, esteemed Sir, that I received your very welcome letter with its learned comments on Boyle’s book. The author himself joins with me in thanking you most warmly for the thoughts you have shared with us, and would have indicated this more quickly had he not entertained the hope that he might soon be relieved of the quantity of business with which he is burdened so that he could have sent you his reply along with his thanks at the same time. However, so far he finds himself disappointed of this hope, being so pressed by both public and private business that at present he can do no more than convey his gratitude to you, and is compelled to defer to another time his opinion on your comments. Furthermore, two opponents have attacked him in print, and he thinks himself bound to reply to them at the first opportunity. These writings are directed not against his Essay on Nitre but against another book of his containing his Pneumatic Experiments,²⁹ proving the elasticity of air. As soon as he has extricated himself from these labours he will also disclose to you his thoughts on your objections. Meanwhile he asks you not to take amiss this delay.

The College of Philosophers of which I spoke to you has now, by our King’s grace, been converted into a Royal Society and presented with the public charter³⁰ whereby it is granted special privileges, and there is a very good prospect that it will be endowed with the necessary funds.

I would by all means urge you not to begrudge scholars the learned fruits of your acute understanding both in philosophy and theology, but to let them be published despite the growlings of pseudo-theologians. Your republic is quite free, and in it philosophy should be pursued quite freely; but your own prudence will suggest to you that you express your ideas and opinions as moderately as you can, and for the rest leave the outcome to fate.

Come, then, excellent Sir, away with all fear of stirring up the pygmies of our time. Long enough have we propitiated ignorance and nonsense. Let us spread the sails of true knowledge and search more deeply than ever before into Nature’s mysteries. Your reflections, I imagine, can be printed in your country with impunity, and there is no need to fear that they will give any offence to the wise. If you find such to be your patrons and supporters (as I am quite sure that you will find them), why should you dread an ignorant Momus? I will not let you go, honoured friend, until I have prevailed on you, and never will I permit, as far as in me lies, that your thoughts, which are of such importance, should be buried in eternal silence. I urgently request you to be good enough to let me know, as soon as you conveniently can, what are your intentions in this matter.

Perhaps things will be happening here not unworthy of your notice. The aforementioned Society will now more vigorously pursue its purpose, and maybe, provided that peace lasts in these shores, it will grace the Republic of Letters with distinction. Farewell, distinguished Sir, and believe me to be,

LETTER 8
To the esteemed B.d.S., from Simon de Vries

[Printed in the O.P. The original is extant. There are certain omissions in the O.P. text.]

I have long wished to pay you a visit, but the weather and the hard winter have not favoured me. Sometimes I bewail my lot, in that the distance between us keeps us so far apart from one another. Fortunate, yes, most fortunate is your companion Casuarius³¹ who dwells beneath the same roof, and can converse with you on the highest matters at breakfast, at dinner, and on your walks. But although we are physically so far apart, you have frequently been present in my thoughts, especially when I am immersed in your writings and hold them in my hand. But since not everything is quite clear to the members of our group (which is why we have resumed our meetings), and in order that you may not think that I have forgotten you, I have set myself to write this letter.

As for our group, our procedure is as follows. One member (each has his turn) does the reading, explains how he understands it, and goes on to a complete demonstration, following the sequence and order of your propositions. Then if it should happen that we cannot satisfy one another, we have deemed it worthwhile to make a note of it and to write to you so that, if possible, it should be made clearer to us and we may, under your guidance, uphold truth against those who are religious and Christian in a superstitious way, and may stand firm against the onslaught of the whole world.

So, when the definitions did not all seem clear to us on our first reading and explaining them, we were not in agreement as to the nature of definition. In this situation, in your absence, we consulted a certain author, a mathematician named Borelli.³² In his discussion of the nature of definition, axiom and postulate, he also cites the opinions of others on this subject. His own opinion goes as follows: “Definitions are employed in a proof as premisses. So they must be quite clearly known; otherwise knowledge that is scientific or absolutely certain cannot be acquired from them.” In another place he writes: “In the case of any subject, the principle of its structure, or its prime and best known essential feature, must be chosen not at random but with the greatest care. For if the construction and feature named is impossible, then the result will not be a scientific definition. For instance, if one were to say, ‘Let two straight lines enclosing a space be called figurals’, the definitions would be of non-entities, and would be impossible. Therefore from these it is ignorance, not knowledge, that would be deduced. Again, if the construction or feature named is indeed possible and true, but unknown to us or doubtful, then the definition will not be sound. For conclusions that derive from what is unknown and doubtful are also uncertain and doubtful, and therefore afford us mere conjecture or opinion, and not sure knowledge.”

Tacquet³³ seems to disagree with this view; he asserts, as you know, that it is possible to proceed directly from a false proposition to a true conclusion. Clavius,³⁴ whose view he (Borelli) also introduces, thinks as follows: “Definitions are arbitrary terms, and there is no need to give the grounds for choosing that a thing should be defined in this way or that. It is sufficient that the thing defined should never be asserted to agree with anything unless it is first proved that the given definition agrees with that same thing.” So Borelli maintains that the definition of any subject must consist of a feature or structure which is prime, essential, best known to us, and true, whereas Clavius holds that it matters not whether it be prime, or best known, or true or not, as long as it is not asserted that the definition we have given agrees with some thing unless it is first provided that the given definition agrees with that same thing. We are inclined to favour Borelli’s view, but we are not sure whether you, Sir, agree with either or neither. Therefore, with such various conflicting views being advanced on the nature of definition—which is accounted as one of the principles of demonstration—and since the mind, if not freed from difficulties surrounding definition, will be in like difficulty regarding deductions made from it, we would very much like you, Sir, to write to us (if we are not giving you too much trouble and your time allows) giving your opinion on the matter, and also on the difference between axioms and definitions. Borelli admits no real distinction other than the name; you, I believe, maintain that there is another difference.

Next, the third Definition³⁵ is not sufficiently clear to us. I brought forward as an example what you, Sir, said to me at the Hague, to wit, that a thing can be considered in two ways: either as it is in itself, or in relation to another thing. For instance, the intellect; for it can be considered either under Thought or as consisting of ideas. But we do not quite see what difference could be here. For we consider that, if we rightly conceive Thought, we ought to comprehend it under ideas, because with the removal of all ideas we would destroy Thought. So the example not being sufficiently clear to us, the matter still remains somewhat obscure, and we stand in need of further explanation.

Finally, at the beginning of the third Scholium to Proposition 8,³⁶ we read: “Hence it is clear that, although two attributes may be conceived as really distinct (that is, the one without the aid of the other), it does not follow that they constitute two entities or two different substances. The reason is that it is of the nature of substance that all its attributes—each one individually—are conceived through themselves, since they have been in it simultaneously.” In this way you seem, Sir, to suppose that the nature of substance is so constituted that it can have several attributes, which you have not yet proved, unless you are referring to the fifth definition³⁷ of absolutely infinite substance or God. Otherwise, if I were to say that each substance has only one attribute, I could rightly conclude that where there are two different attributes there are two different substances. We would ask you for a clearer explanation of this.

Next, I am most grateful for your writings which were conveyed to me by P. Balling and gave me great pleasure, particularly the Scholium to Proposition 19.³⁸ If I can here serve you, too, in any way which is within my power, I am yours to command. You need only let me know. I have begun a course of anatomy, and am about half way through. When it is completed, I shall begin chemistry, and thus following your advice I shall go through the whole medical course. I must stop now, and await your reply. Accept my greetings, who am,

LETTER 9
To the learned young man Simon de Vries, from B.d.S.

[Printed in the O.P. The original is extant. The O.P. text is an abridged version of the original, and the last paragraph appears only in the Dutch edition of the O.P. The letter is undated. A conjectural date is February 1663.]

I have received your letter, long looked for, for which, and for your cordial feelings towards me, accept my warmest thanks. Your long absence has been no less regretted by me than by you, but at any rate I am glad that my late-night studies are of use to you and our friends, for in this way I talk with you while we are apart. There is no reason for you to envy Casearius. Indeed, there is no one who is more of a trouble to me, and no one with whom I have had to be more on my guard. So I should like you and all our acquaintances not to communicate my opinions to him until he will have reached a more mature age. As yet he is too boyish, unstable, and eager for novelty rather than for truth. Still, I am hopeful that he will correct these youthful faults in a few years time. Indeed, as far as I can judge from his character, I am reasonably sure of this; and so his nature wins my affection.

As to the questions raised in your group (which is sensibly organised), I see that your difficulties result from your failure to distinguish between the kinds of definition. There is the definition that serves to explicate a thing whose essence alone is in question and the subject of doubt, and there is the definition which is put forward simply for examination. The former, since it has a determinate object, must be a true definition, while this need not be so in the latter case. For example, if someone were to ask me for a description of Solomon’s temple, I ought to give him a true description, unless I propose to talk nonsense with him. But if I have in my own mind formed the design of a temple that I want to build, and from its description I conclude that I will have to purchase such-and-such a site and so many thousands of stones and other materials, will any sane person tell me that I have reached a wrong conclusion because my definition may be incorrect? Or will anyone demand that I prove my definition? Such a person would simply be telling me that I had not conceived that which in fact I had conceived, or he would be requiring me to prove that I had conceived that which I had conceived, which is utter nonsense. Therefore a definition either explicates a thing as it exists outside the intellect—and then it should be a true definition, differing from a proposition or axiom only in that the former is concerned only with the essences of things or the essences of the affections of things, whereas the latter has a wider scope, extending also to eternal truths—or it explicates a thing as it is conceived by us, or can be conceived. And in that case it also differs from an axiom and proposition in requiring merely that it be conceived, not conceived as true, as in the case of an axiom. So then a bad definition is one which is not conceived.

To make this clearer, I shall take Borelli’s example of a man who says that two straight lines enclosing an area are to be called figurals. If he means by a straight line what everybody else means by a curved line, his definition is quite sound (for the figure intended by the definition would be [as shown] or some such figure), provided that he does not at a later stage mean a square or any other such figure. But if by a straight line he means what we all mean, the thing is plainly inconceivable, and so there is no definition. All these considerations are confused by Borelli, whose view you are too much inclined to embrace.

Here is another example, the one which you adduce towards the end of your letter. If I say that each substance has only one attribute, this is mere assertion unsupported by proof. But if I say that by substance I mean that which consists of only one attribute, this is a sound definition, provided that entities consisting of more than one attribute are thereafter given a name other than substance.

In saying that I do not prove that a substance (or an entity) can have more than one attribute, it may be that you have not given sufficient attention to the proofs. I advanced two proofs, the first of which is as follows: It is clear beyond all doubt that every entity is conceived by us under some attribute, and the more reality or being an entity has, the more attributes are to be attributed to it. Hence an absolutely infinite entity must be defined … and so on. A second proof—and this proof I take to be decisive—states that the more attributes I attribute to any entity, the more existence I am bound to attribute to it; that is, the more I conceive it as truly existent. The exact contrary would be the case if I had imagined a chimera or something of the sort.

As to your saying that you do not conceive thought otherwise than under ideas because thought vanishes with the removal of ideas, I believe that you experience this because when you, as a thinking thing, do as you say, you are banishing all your thoughts and conceptions. So it is not surprising that when you have banished all your thoughts, there is nothing left for you to think. But as to the point at issue, I think I have demonstrated with sufficient clarity and certainty that the intellect, even though infinite, belongs to Natura naturata, not to Natura naturans.³⁹

Furthermore, I fail to see what this has to do with understanding the Third Definition,⁴⁰ or why this definition causes you difficulty. The definition as I gave it to you runs, if I am not mistaken, “By substance I understand that which is in itself and is conceived through itself; that is, that whose conception does not involve the conception of another thing. I understand the same by attribute, except that attribute is so called in respect to the intellect, which attributes to substance a certain specific kind of nature.” This definition, I repeat, explains clearly what I mean by substance or attribute. However, you want me to explain by example—though it is not at all necessary—how one and the same thing can be signified by two names. Not to appear ungenerous, I will give you two examples. First, by ‘Israel’ I mean the third patriarch: by ‘Jacob’ I mean that same person, the latter name being given to him because he seized his brother’s heel.⁴¹ Secondly, by a ‘plane surface’ I mean one that reflects all rays of light without any change. I mean the same by ‘white surface’, except that it is called white in respect of a man looking at it.

With this I think that I have fully answered your questions. Meanwhile I shall wait to hear your judgment. And if there is anything else which you consider to be not well or clearly enough explained, do not hesitate to point it out to me, etc.

LETTER 10
To the learned young man Simon de Vries, from B.d.S.

[Known only from the O.P. The original is lost. Undated. A conjectural date is March 1663.]

You ask me whether we need experience to know whether the definition of some attribute be true. To this I reply that we need experience only in the case of those things that cannot be deduced from the definition of a thing, as, for instance, the existence of modes; for this cannot be deduced from a thing’s definition. We do not need experience in the case of those things whose existence is not distinguished from their essence and is therefore deduced from their definition. Indeed, no experience will ever be able to tell us this, for experience does not teach us the essences of things. The most it can do is to determine our minds to think only about the certain essences of things. So since the existence of attributes does not differ from their essence, we shall not be able to apprehend it by any experience.

As to your further question as to whether things or the affections of things are also eternal truths, I say, most certainly. If you go on to ask why I do not call them eternal truths, I reply, in order to mark a distinction, universally accepted, between these and the truths which do not explicate a thing or the affection of a thing, as, for instance, ‘nothing comes from nothing’. This and similar propositions, I say, are called eternal truths in an absolute sense, by which title is meant simply that they do not have any place outside the mind, etc.

LETTER 11
To the esteemed B.d.S., from Henry Oldenburg

[Known only from the O.P. The original is lost.]

I could produce many excuses for my long silence, but I shall reduce my reasons to two: the illness of the illustrious Mr. Boyle and the pressures of my own business. The former has prevented Boyle from replying to your Observations on Nitre at an earlier date; the latter have kept me so busy over several months that I have scarcely been my own master, and so I have been unable to discharge the duty which I declare I owe you. I rejoice that, for the time at least, both obstacles are removed, so that I can resume my correspondence with so close a friend. This I now do with the greatest pleasure, and I am resolved, with Heaven’s help, to do everything to ensure that our epistolary intercourse shall never in future suffer so long an interruption.

Before I deal with matters what concern just you and me alone, let me deliver what is due to you on Mr. Boyle’s account. The observations which you composed on his short Chemical-Physical Treatise he has received with his customary good nature, and sends you his warmest thanks for your criticism. But first he wants you to know that it was not his intention to demonstrate that this is a truly philosophical and complete analysis of Nitre, but rather to make the point that the common doctrine of Substantial Forms and Qualities accepted in the Schools rests on a weak foundation, and that what they call the specific differences of things can be reduced to the magnitude, motion, rest and position of the parts.

With this preliminary remark, our Author goes on to say that his experiment with Nitre shows quite clearly that through chemical analysis the whole body of Nitre was resolved into parts which differed from one another and from the original whole, and that afterwards it was so reconstituted and redintegrated from these same parts that it lacked little of its original weight. He adds that he has shown this to be a fact, but he has not been concerned with the way in which it comes about, which seems to be the subject of your conjectures, and that he has reached no conclusion on that matter, since that went beyond his purpose. However, as to what you suppose to be the way in which it comes about, and your view that the fixed salt of Nitre is its dregs and other such theories, he considers that these are merely unproved speculations. And as to your idea that these dregs, or this fixed salt, has openings hollowed out to the size of the particles of Nitre, on this subject our Author points out that salt of potash combined with Spirit of Nitre constitutes Nitre just as well as Spirit of Nitre combined with its own fixed salt. Hence he thinks it clear that similar pores are to be found in bodies of that kind, from which nitrous spirits are not given off. Nor does the Author see that the necessity for the very fine matter, which you allege, is proved from any of the phenomena, but he says it is assumed simply from the hypothesis of the impossibility of a vacuum.

The Author says that your remarks on the causes of the difference of taste between Spirit of Nitre and Nitre do not affect him; and as to what you say about the inflammability of Nitre and the non-inflammability of Spirit of Nitre, he says that this presupposes Descartes’ theory of fire,⁴² with which he declares he is not yet satisfied.

With regard to the experiments which you think confirm your explanation of the phenomenon, the Author replies that (1) Spirit of Nitre is indeed Nitre in respect of its matter, but not in respect of its form, since they are vastly different in their qualities and properties, viz. in taste, smell, volatility, power of dissolving metals, changing the colours of vegetables, etc. (2) When you say that some particles carried upwards coalesce into crystals of Nitre, he maintains that this happens because the nitrous parts are driven off through the fire along with Spirit of Nitre, as is the case with soot. (3) As to your point about the effect of purification, the Author replies that through that purification the Nitre is for the most part freed from a certain salt which resembles common salt, and that its ascending to form icicles is something it has in common with other salts, and depends on air pressure and other causes which must be discussed elsewhere and have no bearing on the present question. (4) With regard to your remarks on your third experiment, the Author says that the same thing occurs with certain other salts. He asserts that when the paper is actually alight, it sets in motion the rigid and solid particles composing the salt and in this way causes them to sparkle.

Next, when you think that in the fifth section the noble Author is criticising Descartes, he believes that you yourself are here at fault. He says that he was in no way referring to Descartes, but to Gassendi and others who attribute to Nitre a cylindrical shape when it is in fact prismatic, and that he is speaking only of visible shapes.

To your comments on sections 13–18, he merely replies that he wrote these sections with this main object, to demonstrate and assert the usefulness of chemistry in confirming the mechanical principles of philosophy, and that he has not found these matters so clearly conveyed and treated by others. Our Boyle belongs to the class of those who do not have so much trust in their reason as not to want phenomena to agree with reason. Moreover, he says that there is a considerable difference between superficial experiments where we do not know what Nature contributes and what other factors intervene, and those experiments where it is established with certainty what are the factors concerned. Pieces of wood are much more composite bodies than the subject dealt with by the Author. And in the case of ordinary boiling water fire is an additional external factor, which is not so in the production of our sound. Again, the reason why green vegetation changes into so many different colours is still being sought, but that this is due to the change of the parts is established by this experiment, which shows that the change of colour was due to the addition of Spirit of Nitre. Finally, he says that Nitre has neither a foul nor a sweet smell; it acquires a foul smell simply as a result of its decomposition, and loses it when it is recompounded.

With regard to your comments on section 25 (the rest, he says, does not touch him) he replies that he has made use of the Epicurean principles which hold that there is an innate motion in particles; for he needed to make use of some hypothesis to explain the phenomenon. Still, he does not on that account adopt it as his own, but he uses it to support his view against the chemists and the Schools, demonstrating merely that the facts can be well explained on the basis of the said hypothesis. As to your additional remark at the same place on the inability of pure water to dissolve the fixed parts, our Boyle replies that it is the general opinion of chemists from their observations that pure water dissolves alkaline salts more rapidly than others.

The Author has not yet had time to consider your comments on fluidity and solidity. I am sending you what I here enclose so that I may not any longer be deprived of intercourse and correspondence with you. But I do most earnestly beg you to take in good part what I here pass on to you in such a disjointed and disconnected way, and to ascribe this to my haste rather than to the character of the illustrious Boyle. For I have assembled these comments as a result of informal talk with him on this subject rather than from any deliberate and methodical reply on his part. Consequently, many things which he said have doubtless escaped me, which were perhaps more substantial and better expressed than what I have here set down. All blame, therefore, I take on my own shoulders, and entirely absolve the Author.

Now I shall turn to matters that concern you and me, and here at the outset let me be permitted to ask whether you have completed that little work of such great importance, in which you treat of the origin of things and their dependence on a first cause, and also of the emendation of our intellect. Of a surety, my dear friend, I believe that nothing can be published more agreeable and more welcome to men who are truly learned and wise than a treatise of that kind. That is what a man of your talent and character should look to, rather than what pleases the theologians of our age and fashion. They look not so much to truth as to what suits them. So I urge you by our bond of friendship, by all the duties we have to promote and disseminate truth, not to begrudge or deny us your writings on these subjects. If, however, there is some consideration of greater weight than I can foresee which holds you back from publishing the work, I heartily beg you to be pleased to let me have by letter a summary of it, and for this service you will find me a grateful friend. There will soon be more publications⁴³ from the learned Boyle which I shall send you by way of requital, adding an account of the entire constitution of our Royal Society, of whose Council I am a member with twenty others, and joint secretary with one other. At present lack of time prevents me from going on to other matters. To you I pledge all the loyalty that can come from an honest heart, and an entire readiness to do you any service that lies within my slender powers, and I am, sincerely,

LETTER 12
To the learned and wise Lodewijk Meyer, Doctor of Medicine and Philosophy, from B.d.S.

[Printed in the O.P. The original is lost, but a copy made by Leibniz has been preserved.]

I have received two letters from you, one dated January 11 and delivered to me by our friend N.N.,⁴⁴ the other dated March 26 and sent to me by an unknown friend from Leiden. They were both very welcome, especially as I gathered from them that all is well with you and that I am often in your thoughts. My most cordial thanks are due to you for the kindness and esteem you have always seen fit to show me. At the same time I beg you to believe that I am no less your devoted friend, and this I shall endeavour to prove whenever the occasion arises, as far as my slender abilities allow. As a first offering, I shall try to answer the request made to me in your letters, in which you ask me to let you have my considered views on the question of the infinite. I am glad to oblige.

The question of the infinite has universally been found to be very difficult, indeed, insoluble, through failure to distinguish between that which must be infinite by its very nature or by virtue of its definition, and that which is unlimited not by virtue of its essence but by virtue of its cause. Then again, there is the failure to distinguish between that which is called infinite because it is unlimited, and that whose parts cannot be equated with or explicated by any number, although we may know its maximum or minimum. Lastly, there is the failure to distinguish between that which we can apprehend only by the intellect and not by the imagination, and that which can also be apprehended by the imagination. I repeat, if men had paid careful attention to these distinctions, they would never have found themselves overwhelmed by such a throng of difficulties. They would clearly have understood what kind of infinite cannot be divided into, or possess any, parts, and what kind can be so divided without contradiction. Again, they would also have understood what kind of infinite can be conceived, without illogicality, as greater than another infinite, and what kind cannot be so conceived. This will become clear from what I am about to say. However, I shall first briefly explain these four terms: Substance, Mode, Eternity, Duration.

The points to be noted about Substance are as follows. First, existence pertains to its essence; that is, solely from its essence and definition it follows that Substance exists. This point, if my memory does not deceive me, I have proved to you in an earlier conversation without the help of any other propositions. Second, following from the first point, Substance is not manifold; rather there exists only one Substance of the same nature. Thirdly, no Substance can be conceived as other than infinite.⁴⁵

The affections of Substance I call Modes. The definition of Modes, insofar as it is not itself a definition of Substance, cannot involve existence. Therefore, even when they exist, we can conceive them as not existing. From this it further follows that when we have regard only to the essence of Modes and not to the order of Nature as a whole, we cannot deduce from their present existence that they will or will not exist in the future or that they did or did not exist in the past. Hence it is clear that we conceive the existence of Substance as of an entirely different kind from the existence of Modes. This is the source of the difference between Eternity and Duration. It is to the existence of Modes alone that we can apply the term Duration; the corresponding term for the existence of Substance is Eternity, that is, the infinite enjoyment of existence or—pardon the Latin—of being (essendi).

What I have said makes it quite clear that when we have regard only to the essence of Modes and not to Nature’s order, as is most often the case, we can arbitrarily delimit the existence and duration of Modes without thereby impairing to any extent our conception of them; and we can conceive this duration as greater or less, and divisible into parts. But Eternity and Substance, being conceivable only as infinite, cannot be thus treated without annulling our conception of them. So it is nonsense, bordering on madness, to hold that extended Substance is composed of parts or bodies really distinct from one another. It is as if, by simply adding circle to circle and piling one on top of another, one were to attempt to construct a square or a triangle or any other figure of a completely different nature. Therefore the whole conglomeration of arguments whereby philosophers commonly strive to prove that extended Substance is finite collapses of its own accord. All such arguments assume that corporeal Substance is made up of parts. A parallel case is presented by those who, having convinced themselves that a line is made up of points,⁴⁶ have devised many arguments to prove that a line is not infinitely divisible.

However, if you ask why we have such a strong natural tendency to divide extended Substance, I answer that we conceive quantity in two ways: abstractly or superficially, as we have it in the imagination with the help of the senses, or as Substance, apprehended solely by means of the intellect. So if we have regard to quantity as it exists in the imagination (and this is what we most frequently and readily do), it will be found to be divisible, finite, composed of parts, and manifold. But if we have regard to it as it is in the intellect and we apprehend the thing as it is in itself (and this is very difficult), then it is found to be infinite, indivisible, and one alone, as I have already sufficiently proved.

Further, from the fact that we are able to delimit Duration and Quantity as we please, conceiving Quantity in abstraction from Substance and separating the efflux of Duration from things eternal, there arise Time and Measure: Time to delimit Duration and Measure to delimit Quantity in such wise as enables us to imagine them easily, as far as possible. Again, from the fact that we separate the affections of Substance from Substance itself, and arrange them in classes so that we can easily imagine them as far as possible, there arises Number, whereby we delimit them. Hence it can clearly be seen that Measure, Time and Number are nothing other than modes of thinking, or rather, modes of imagining. It is therefore not surprising that all who have attempted to understand the workings of Nature by such concepts, and furthermore without really understanding these concepts, have tied themselves into such extraordinary knots that in the end they have been unable to extricate themselves except by breaking through everything and perpetrating the grossest absurdities. For there are many things that can in no way be apprehended by the imagination but only by the intellect, such as Substance, Eternity, and other things. If anyone tries to explicate such things by notions of this kind which are nothing more than aids to the imagination, he will meet with no more success than if he were deliberately to encourage his imagination to run mad. Nor again can the Modes of Substance every be correctly understood if they are confused with such mental constructs (entia rationis) or aids to the imagination. For by so doing we are separating them from Substance and from the manner of their efflux from Eternity, and in such isolation they can never be correctly understood.

To make the matter still clearer, take the following example. If someone conceives Duration in this abstracted way and, confusing it with Time, begins dividing it into parts, he can never understand how an hour, for instance, can pass by. For in order that an hour should pass by, a half-hour must first pass by, and then half of the remainder, and the half of what is left; and if you go on thus subtracting half of the remainder to infinity, you can never reach the end of the hour. Therefore many who are not used to distinguishing mental constructs from real things have ventured to assert that Duration is composed of moments, thus falling into the clutches of Scylla in their eagerness to avoid Charybdis. For to say that Duration is made up of moments is the same as to say that Number is made up simply by adding noughts together.

Further, it is obvious from the above that neither Number, Measure, nor Time, being merely aids to the imagination, can be infinite, for in that case Number would not be number, nor Measure measure, nor Time time. Hence one can easily see why many people, confusing these three concepts with reality because of their ignorance of the true nature of reality, have denied the actual existence of the infinite. But let their deplorable reasoning be judged by mathematicians who, in matters that they clearly and distinctly perceive, are not to be put off by arguments of that sort. For not only have they come upon many things inexpressible by any number (which clearly reveals the inadequacy of number to determine all things) but they also have many instances which cannot be equated with any number, and exceed any possible number. Yet they do not draw the conclusion that it is because of the multitude of parts that such things exceed all number; rather, it is because the nature of the thing is such that number is inapplicable to it without manifest contradiction.

For example, all the inequalities of the space lying between the two circles ABCD in the diagram exceed any number, as do all the variations of the speed of matter moving through that area. Now this conclusion is not reached because of the excessive magnitude of the intervening space; for however small a portion of it we take, the inequalities of this small portion will still be beyond any numerical expression. Nor again is this conclusion reached, as happens in other cases, because we do not know the maximum and minimum; in our example we know them both, the maximum being AB and the minimum CD. Our conclusion is reached because number is not applicable to the nature of the space between two non-concentric circles. Therefore if anyone sought to express all those inequalities by a definite number, he would also have to bring it about that a circle should not be a circle.

Similarly, to return to our theme, if anyone were to attempt to determine all the motions of matter that have ever been, reducing them and their duration to a definite number and time, he would surely be attempting to deprive corporeal Substance, which we cannot conceive as other than existing, of its affections, and to bring it about that Substance should not possess the nature which it does possess. I could here clearly demonstrate this and many other points touched on in this letter, did I not consider it unnecessary.

From all that I have said one can clearly see that certain things are infinite by their own nature and cannot in any way be conceived as finite, while other things are infinite by virtue of the cause in which they inhere; and when the latter are conceived in abstraction, they can be divided into parts and be regarded as finite. Finally, there are things that can be called infinite, or if you prefer, indefinite, because they cannot be accurately expressed by any number, while yet being conceivable as greater or less. For it does not follow that things which cannot be adequately expressed by any number must necessarily be equal, as is sufficiently evident from the given example and from many others.

To sum up, I have here briefly set before you the causes of the errors and confusion that have arisen regarding the question of the infinite, explaining them all, unless I am mistaken, in such a way that I do not believe there remains any question regarding the Infinite on which I have not touched, or which cannot be readily solved from what I have said. Therefore I do not think there is any point in detaining you longer on this matter.

However, in passing I should like it here to be observed that in my opinion our modern Peripatetics have quite misunderstood the demonstration whereby scholars of old sought to prove the existence of God. For, as I find it in a certain Jew named Rab Chasdai,⁴⁷ this proof runs as follows: “If there is granted an infinite series of causes, all things which are, are also caused. But nothing that is caused can exist necessarily by virtue of its own nature. Therefore there is nothing in Nature to whose essence existence necessarily pertains. But this latter is absurd; therefore also the former.”⁴⁸ So the force of the argument lies not in the impossibility of an actual infinite or an infinite series of causes, but only in the assumption that things which by their own nature do not necessarily exist are not determined to exist by a thing which necessarily exists by its own nature.

I would now pass on—for I am pressed for time—to your second letter, but I shall be able more conveniently to reply to the points contained therein when you will kindly pay me a visit. So do please try to come as soon as you possibly can. For the time of my moving is rapidly approaching. Enough, farewell, and keep me ever in your thoughts, who am, etc.

LETTER 12A
To Lodewijk Meyer, from B.d.S.

[Not in the O.P. nor in Gebhardt. Discovered by Offenberg and published in 1975.]

Yesterday I received your very welcome letter in which you ask, first, whether in Chapter 2 of Part I of the Appendix you have correctly indicated all propositions, etc., which are there cited from Part I of the Principia; secondly, whether my assertion in Part II that the Son of God is the Father himself should not be deleted; and finally, whether my statement that I do not know what theologians understand by the term ‘personalitas’ should not be changed. To this I reply,

1. That everything you have indicated in Chapter 2 of the Appendix has been correctly indicated. But in Chapter 1 of the Appendix, page 1, you have indicated the Scholium to Proposition 4, whereas I would prefer you to have indicated the Scholium to Proposition 15, where my declared purpose is to discuss all modes of thinking. Again, on page 2 of the same chapter, you have written these words in the margin, ‘Why negations are not ideae,’ where the word ‘negations’ should be replaced by ‘entia rationis’, for I am speaking of the ‘ens rationis’ in general, and saying that it is not an ‘idea.’

2. As to my saying that the Son of God is the Father himself, I think it follows clearly from this axiom, namely, that things which agree with a third thing agree with one another. However, since this is a matter of no importance to me, if you think that it may give offence to some theologians, do as seems best to you.

3. Finally, what theologians mean by the word ‘personalitas’ is beyond me, though I know what philologists mean by it. Anyway, since the manuscript is in your hands, you can better decide these things yourself. If you think they ought to be changed, do as you please.

LETTER 13
To the noble and learned Henry Oldenburg, from B.d.S.

[Known only from the O.P. The original is lost.]

Your letter, which I have long looked for, I have at last received, and am also free to answer it. But before embarking on this task, I shall briefly relate the circumstances which have prevented an earlier reply.

When I moved my furniture here in April, I went to Amsterdam. There some of my friends requested me to provide them with a transcript of a certain treatise containing a short account of the Second Part of Descartes’ Principles demonstrated in geometric style, and the main topics treated in metaphysics, which I had previously dictated to a young man⁴⁹ to whom I did not wish to teach my own opinions openly. Then they asked me to prepare the First Part too by the same method, as soon as I could. Not to disappoint my friends, I immediately set about this work, completed it in two weeks and delivered it to my friends, who finally asked my permission to publish the whole thing. They readily obtained my consent, but on condition that one of them, in my presence, should give it a more elegant style and add a short preface warning readers that I do not acknowledge everything in the treatise as my own views, ‘since I have written in quite a few things which are completely opposed to my own opinions’, and should illustrate this fact by one or two examples. One of my friends who has undertaken the publication of this little book has promised to do all this,⁵⁰ and that is why I was delayed at Amsterdam for some time. And right from the time of my return to this village where I now live, I have scarcely been my own master because of friends who have been kind enough to call on me.

Now at last, my very dear friend, I have time enough to tell you this, and also to give you the reason why I am allowing this treatise to be published. Perhaps as a result there will be some men holding high positions in my country who will want to see other of my writing which I acknowledge as my own, and so will arrange that I can make them available to the public without risk of trouble. Should this come about, I have no doubt that I shall publish some things immediately; if not, I shall keep silent rather than thrust my opinions on men against my Country’s wishes and incur their hostility. I therefore beg you, my honoured friend, to be patient until that time; for then you will either have the treatise in print or a summary of it, as you request. And if in the meantime you would like one or two copies of the work which is now in the press, when I am told so and I also find a convenient way of sending it, I shall comply with your wish.

I now turn to your letter. I thank you most warmly, as I should, and also the noble Boyle, for your outstanding kindness towards me and your goodwill. The many affairs in which you are engaged, of such weight and importance, have not made you unmindful of your friend, and indeed you generously promise that you will make every effort in future to avoid so long an interruption in our correspondence. The learned Mr. Boyle, too, I thank very much for being so good as to reply to my observations, in however cursory and preoccupied a way. I do indeed admit that they are not of such importance that the learned gentleman, in replying to them, should spend time which he can devote to reflections of a higher kind. For my part I did not imagine—indeed, I could never have been convinced—that the learned gentleman had no other object in view in his Treatise on Nitre than merely to demonstrate that the puerile and frivolous doctrine of Substantial Forms and Qualities rests on a weak foundation. But being convinced that it was the esteemed Boyle’s intention to explain to us the nature of Nitre, that it was a heterogeneous body consisting of fixed and volatile parts, I intended in my explanation to show (as I think I have more than adequately shown) that we can quite easily explain all the phenomena of Nitre, such as are known to me at least, while regarding Nitre as a homogeneous body, not heterogeneous. Therefore it was not for me to prove, but merely to hypothesize, that the fixed salt is the dregs of Nitre, so that I might see how the esteemed Mr. Boyle could prove to me that this salt is not the dregs but a very necessary constituent in the essence of Nitre without which it could not be conceived. For this, as I say, I thought to be the object of the esteemed Mr. Boyle’s demonstration.

When I said that the fixed salt has passages hollowed out according to the dimensions of the particles of Nitre, I did not need this to explain the redintegration of Nitre. For from my assertion that its redintegration consists merely in the coagulation of the Spirit of Nitre, it is apparent that every calx whose passages are too narrow to contain the particles of Nitre and whose walls are weak is well fitted to halt the motion of the particles of Nitre, and therefore, by my hypothesis, to redintegrate the Nitre itself. So it is not surprising that there are other salts, such as tartar and potash, with whose aid Nitre can be redintegrated. My only purpose in saying that the fixed salt of Nitre has passages hollowed out in accord with the dimensions of the particles of Nitre was to assign a reason why the fixed salt of Nitre is more suited to redintegrate Nitre without much loss of its original weight. Indeed, from the fact that there are other salts from which Nitre can be redintegrated, I thought I might show that the calx of Nitre is not necessary for constituting the essence of Nitre, if the esteemed Mr. Boyle had not said that there is no salt more universal than Nitre; and so it might have lain concealed in tartar and potash.

When I further said that the particles of Nitre in the larger passages are encompassed by finer matter, I inferred this, as the esteemed Mr. Boyle says, from the impossibility of a vacuum. But I do not know why he calls the impossibility of a vacuum a hypothesis, since it clearly follows from the fact that nothing has no properties. And I am surprised that the esteemed Mr. Boyle doubts this, since he seems to hold that there are no real accidents. Would there not be a real accident, I ask, if Quantity were granted without Substance.

With regard to the causes of the difference of taste between Spirit of Nitre and Nitre itself, I had to suggest these so as to show how I could quite easily explain the phenomena of Nitre merely as a result of the difference I was willing to allow between Spirit of Nitre and Nitre itself, taking no account of the fixed salt.

My remarks as to the inflammability of Nitre and the noninflammability of Spirit of Nitre do not presuppose anything other than that for kindling of a flame in any body there needs be some matter that can separate and set in motion the parts of the body, both of which facts I think are sufficiently taught us by daily experience and reason.

I pass on to the experiments which I put forward so as to confirm my explanation not in any absolute sense but, as I expressly said, to some degree. Against the first experiment which I adduced, the esteemed Mr. Boyle advances nothing beyond what I myself have most expressly remarked. As for the others which I also attempted so as to free from suspicion that which the esteemed Mr. Boyle joins me in noting, he has nothing whatever to say. As to his remarks on the second experiment, to wit, that through purification Nitre is for the most part freed from a salt resembling common salt, this he only says but does not prove. For, as I have expressly said, I did not put forward these experiments to give complete confirmation to my assertions, but only because they seemed to offer some degree of confirmation to which I had said and had shown to be consistent with reason. As to his remark that rising to form little icicles is common to this and to other salts, I do not know how this is relevant; for I grant that other salts also have dregs and are rendered more volatile if they are freed from them. Against the third experiment, too, I see nothing advanced that touches me. In the fifth section I thought that our noble Author was criticising Descartes, which he has also done elsewhere by virtue of the freedom to philosophise granted to everyone without hurt to the reputation of either party. Others, too, who have read the writings of the esteemed Mr. Boyle and Descartes’ Principles may well think like me unless they are expressly warned. And I still do not see that the esteemed Mr. Boyle makes his meaning quite clear; for he still does not say whether Nitre will cease to be Nitre if its visible icicles, of which alone he says he is speaking, were to be rubbed until they changed into parallelepipeds or some other shape.

But leaving these matters, I pass on to the esteemed Mr. Boyle’s assertions in sections 13 … 18. I say that I willingly admit that this redintegration of Nitre is indeed an excellent experiment for investigating the nature of Nitre—that is, when we already know the mechanical principles of philosophy, and that all variations of bodies come about according to the laws of mechanics; but I deny that these things follow from the said experiment more clearly and evidently than from many other commonplace experiments, which do not, however, provide definite proof. As to the esteemed Mr. Boyle’s remark that he has not found these views of his so clearly expounded and discussed by others, perhaps he has something I cannot see against the arguments of Verulam and Descartes whereby he considers he can refute them. I do not cite these arguments here, because I do not imagine that the esteemed Mr. Boyle is unaware of them. But this I will say, that these writers, too, wanted phenomena to accord with their reason; if they nevertheless were mistaken on certain points, they were but men, and I think that nothing human was alien to them.⁵¹

He says, too, that there is a considerable difference between those experiments (that is, the commonplace and doubtful experiments adduced by me) where we do not know what is contributed by Nature and what by other factors, and those where the contributing factors are clearly established. But I still do not see that the esteemed Mr. Boyle has explained to us the nature of the substances that are present in this affair, namely, the nature of the calx of Nitre and the Spirit of Nitre, so that these two seem no less obscure than those which I adduced, namely, common lime and water. As for wood, I grant that it is a more composite body than Nitre; but as long as I do not know the nature of either, and the way in which heat is produced in either of them, what, I ask, does this matter? Again, I do not know by what reasoning the esteemed Mr. Boyle ventures to assert that he knows what Nature contributes in the matter under our consideration. By what reasoning, pray, can he demonstrate to us that the heat was not produced by some very fine matter? Perhaps because there was little lost from the original weight? Even if nothing had been lost, in my opinion no inference could be drawn; for we see how easily things can be dyed some colour as a result of a very small quantity of matter, without thereby becoming heavier or lighter to the senses. Therefore I am justified in entertaining some doubt as to whether there may not have been a concurrence of certain factors imperceptible to the senses, especially while it is not known how all those variations observed by the esteemed Mr. Boyle during the experiments could have arisen from the said bodies. Indeed, I am sure that the heat and the effervescence recounted by the esteemed Mr. Boyle arose from foreign matter.

Again, that disturbance of air is the cause from which sound originates can, I think, be more easily inferred from the boiling of water (I say nothing here of its agitation) than from this experiment where the nature of the concurrent factors is quite unknown, and where heat is also observed without our knowing in what way or from what causes it has originated. Finally, there are many things that emit no smell at all; yet if their parts are to some degree stirred up and become warm, they at once emit a smell; and if again they are cooled, they again have no smell (at least of human sense—perception)—such as amber, and other things which may also be more composite than Nitre.

My remarks on the twenty-fourth section show that Spirit of Nitre is not pure Spirit, but contains much calx of Nitre and other things. So I doubt whether the esteemed Mr. Boyle could have been sufficiently careful in observing what he says he has detected with the aid of scales, namely, that the weight of Spirit of Nitre which he added was roughly equal to the weight lost during detonation.

Finally, although to our eyes pure water can dissolve alkaline salts more rapidly, yet since it is a more homogeneous body than air, it cannot, like air, have so many kinds of corpuscles which can penetrate through the pores of every kind of calx. So since water is made up mostly of definite particles of a single kind which can dissolve calx up to a certain limit—which is not the case with air—it follows that water will dissolve calx up to that limit far more rapidly than air. But on the other hand, since air is made up of both grosser and far finer particles and all kinds of particles which can in many ways get through much narrower pores than can be penetrated by particles of water, it follows that air can dissolve calx of Nitre if not as rapidly as water (because it cannot be made up of so many particles of a particular kind) yet far more effectively and to a finer degree, and render it less active and so more apt to halt the motion of the particles of the Spirit of Nitre. For as yet the experiments do not make me acknowledge any difference between Spirit of Nitre and Nitre itself other than that the particles of the later are at rest, while those of the former are in very lively motion with one another. So the difference between Nitre and Spirit of Nitre is the same as that between ice and water.

But I do not venture to detain you any longer on these matters; I fear I have been too prolix, although I have sought to be as brief as possible. If I have nevertheless been boring, I beg you to forgive me, and at the same time to take in good part which is said frankly and sincerely by a friend. For I judged it wrong, in replying to you, to keep altogether silent on these matters. Yet to praise to you what I could not agree with would have been sheer flattery, than which I deem nothing to be more destructive and damaging in friendships. I therefore resolved to open my mind quite frankly, and in my opinion nothing is more welcome than this to philosophers. Meanwhile, if it seems more advisable to you to consign these thoughts to the fire than to pass them on the learned Mr. Boyle, they are in your hands. Do as you please, so long as you believe me to be a most devoted and loving friend to you and to the noble Mr. Boyle. I am sorry that my slender resources prevent me from showing this otherwise than in words. Still … etc.

LETTER 14
Henry Oldenburg to the esteemed B.d.S.

[Known only from the O.P. The Latin original is lost. In the penultimate paragraph, the last sentence appears only in the Dutch edition of the O.P.]

I find much happiness in the renewal of our correspondence. Know therefore how I rejoiced to receive your letter dated 17/27 July, and particularly on two accounts, that it gave evidence of your well-being and that it assured me of the constancy of your friendship. To crown it all, you tell me that you have committed to the press the first and second parts of Descartes’ Principia demonstrated in the geometric style, while generously offering me one or two copies of it. Most gladly do I accept the gift, and I ask you please to send the treatise now in the press to Mr. Peter Serrarius⁵² living at Amsterdam, for delivery to me. I have arranged with him to receive such a package and to send it on to me by a friend who is making the crossing.

But allow me to say that I am by no means content with your continued suppression of the writings which you acknowledge as your own, especially in a republic so free that there you are permitted to think what you please and to say what you think. I wish you would break through those barriers, especially since you can conceal your name and thus place yourself beyond any risk of danger.

The noble Boyle has gone away: as soon as he returns to town, I shall communicate to him that part of your learned letter which concerns him, and as soon as I have obtained his opinion on your views, I shall write to you again. I think you have already seen his Sceptical Chymist which was published in Latin some time ago and is widely circulated abroad. It contains many Chemico-Physical paradoxes, and subjects the Hypostatical principles of the Spagyrists, as they are called, to a strict examination.⁵³

He has recently published another little book which perhaps has not yet reached your booksellers. So I am sending it to you enclosed herewith, and I ask you as a friend to take in good part this little gift. The booklet, as you will see, contains a defence of the power of elasticity of air against a certain Francis Linus, who busies himself to explain the phenomena recounted in Mr. Boyle’s New Physico-Mechanical Experiments by a thread of argument that eludes the intellect as well as all sense-perception.⁵⁴ Read it, weigh it, and let me know what you think of it.

Our Royal Society is earnestly and actively pursuing its purpose, confining itself within the limits of experiment and observation, avoiding all debatable digressions.

Recently an excellent experiment has been performed which greatly perplexes the upholders of a vacuum but is warmly welcomed by those who hold that space is a plenum. It is as follows. Let a glass flask A, filled to the brim with water, be inverted with its mouth in a glass jar B containing water, and let it be placed in the Receiver of Mr. Boyle’s New Pneumatic Machine. Then let the air be pumped out of the Receiver. Bubbles will be seen to rise in great quantity from the water into the flask A and to force down all the water from these into the jar B below the surface of the water contained therein. Let the two vessels be left in this state for a day or two, the air being repeatedly evacuated from the said Receiver by frequent pumpings. Then let them be removed from the Receiver, and let the flask A be refilled with this water from which air has been removed and again inverted in the jar B, and let both vessels be once more enclosed in the Receiver. When the Receiver has again been emptied by the requisite amount of pumping, perhaps a little bubble will be seen to rise from the neck of the flask A, which, rising to the top and expanding with the continued pumping, will once again force out all the water from the flask, as before. Then let the flask be again taken from the Receiver, filled to the top with water from which the air has been removed, inverted as before, and placed in the Receiver. Then let the Receiver be thoroughly evacuated of air, and when it has been well and truly evacuated, water will remain in the flask in such a state of suspension that it will not descend at all. In this experiment the cause which, according to Boyle, is believed to sustain the water in the Torricellian experiment (namely, the pressure of the air on the water in the vessel B)⁵⁵ seems completely removed, and yet the water in the flask does not descend.⁵⁶

I had intended to add more, but friends and business call me away. I shall only add this: if you would like to send me the things you are having printed, please address your letter and packages in the following way … etc.

I cannot conclude this letter without urging you again and again to publish your own thoughts. I shall not cease to exhort you until you satisfy my request. In the meantime, if you should be willing to let me have some of the main points contained therein, oh! how I would love you and with how close a tie I would hold myself bound to you! May all go well with you, and continue to love me, as you do.

LETTER 15
Cordial greetings to Mr. Lodewijk Meyer, from B. de Spinoza

[Not in the O.P. This letter was discovered by Victor Cousin, and published in 1847.]

The Preface which you sent me through our friend de Vries I now return to you through him. As you will see for yourself, I have made a few notes in the margin; but there still remain a few things which I have thought it better to let you have by letter.

First, where on page 4 you inform the reader of the occasion of my composing the First Part, I should like you also at the same time to point out, either there or wherever you please, that I composed it within two weeks. Thus forewarned, no one will imagine that what I present is so clear that it could not have been expounded more clearly, and so they will not be put out by a mere word or two which in some places they may find obscure.

Second, I should like you to mention that many of my demonstrations are arranged in a way different from that of Descartes, not to correct Descartes, but only the better to preserve my order of exposition and thus to avoid increasing the number of axioms. And it is also for the same reason that I have had to prove many things which Descartes merely asserts without proof, and to add other things which Descartes omitted.

Finally, my very dear friend, I beg you most earnestly to leave out what you wrote at the end against that petty man,⁵⁷ and to delete it entirely. And although I have many reasons for making this request of you, I shall mention only one. I should like everyone to be able readily to accept that this publication is meant for the benefit of all men, and that in publishing this book you are motivated only by a wish to spread the truth, and so you are chiefly concerned to make this little work welcome to all, that you are inviting men in a spirit of goodwill to take up the study of the true philosophy, and your aim is the good of all. This everyone will readily believe when he sees that no one is attacked, and that nothing is advanced which might be offensive to some person. If, however, in due course that person or some other chooses to display his malicious disposition, then you can portray his life and character, and not without approval. I therefore beg you to be good enough to wait until then, and to allow yourself to be persuaded, and to believe me to be your devoted and zealous friend,

Our friend de Vries had promised to take this with him, but since he does not know when he is going back to you, I am sending it by someone else.

I am sending along with this a part of the Scholium to Proposition 27 of Part 2, as it begins on page 75, for you to give to the printer to be typeset again.

What I am here sending you will have to be printed again and 14 or 15 lines must be added, which can easily be inserted.⁵⁸

LETTER 16
2Henry Oldenburg to the esteemed B.d.S.

[Known only from the O.P. The original is lost.]

Scarcely three or four days have passed since I sent you a letter by the ordinary post. In that letter I made mention of a certain booklet written by Mr. Boyle, which has to be sent to you. At that time there appeared no hope of quickly finding a friend to deliver it. Since that time someone has come forward sooner than I expected. So receive now what could not then be sent, together with the dutiful greetings of Mr. Boyle who has now returned to town from the country.

He asks you to consult the preface which he wrote to his Experiments on Nitre, so as to understand the true aim which he set himself in that work: namely, to show that the doctrines of the more firmly grounded philosophy now being revived are elucidated by clear experiments, and that these experiments can very well be explained without the forms, qualities and the futile elements of the Schools.⁵⁹ In no way did he undertake to pronounce on the nature of Nitre, nor again to criticise opinions that may be expressed by anyone about the homogeneity of matter and the differences of bodies arising solely from motion, shape, and so on. He says that he meant only to show this, that the various textures of bodies produce their various differences, and that from these proceed very different effects, and that, as long as there has been no reduction to prime matter, some heterogeneity is properly inferred therefrom by philosophers and others. Nor would I think that there is disagreement between you and Mr. Boyle on the fundamental issue.

As to your saying that any calx, whose passages are too narrow to contain the particles of Nitre and whose walls are weak, is apt to halt the motion of the particles of Nitre and therefore to reconstitute the Nitre, Boyle replies that if Spirit of Nitre is mixed with other kinds of calx, it will not, however, combine with them to form true Nitre.

As to the argument you employ to deny the possibility of a vacuum, Boyle says that he knows it and has seen it before, but is not by any means satisfied with it. He says there will be an opportunity to discuss the matter on another occasion.

He has requested me to ask you whether you can provide him with an example where two odorous bodies, when combined into one, compose a body that is completely odourless, as Nitre is. Such, he says, are the parts composing Nitre; for Spirit of Nitre gives out a foul smell, while fixed Nitre is not without smell.

He further asks you to consider well whether, in comparing ice and water with Nitre and Spirit of Nitre, you are making a proper comparison. For the whole of the ice is resolved only into water, and when the odourless ice turns again into water it remains odourless, whereas the Spirit of Nitre and its fixed salt are found to have different qualities, as the printed Treatise quite clearly tells us.

These and similar things I gathered from our illustrious author in conversation on this subject. I am sure that, through weakness of memory, my recollection does him grave injustice rather than credit. Since you are both in agreement on the main point, I am not inclined to enlarge any further on these matters. I would rather persuade you both to unite your abilities in striving to advance a genuine and firmly based philosophy. May I urge you especially, with your keen mathematical mind, to continue to establish basic principles, just as I ceaselessly try to entice my noble friend Boyle to confirm and elucidate them by experiments and observations repeatedly and accurately made.

You see, my dear friend, what I am striving for, what I am trying to attain. I know that our native philosophers in our kingdom will in no way fail in their duty to experiment, and I am no less convinced that you in your own land will actively do your part, whatever snarlings or accusations may come from the mob of philosophers or theologians. Having already exhorted you to this in numerous previous letters, I will restrain myself lest I weary you. I shall just make this one further request, that you will please send me with all speed by Mr. Serrarius whatever has already been committed to print, whether it be your commentary on Descartes or something drawn from your own intellectual stores. You will have me that much more closely bound to you, and will understand that, under any circumstance, I am,

LETTER 17
To the learned and sagacious Pieter Balling, from B.d.S.

[Known only from the O.P. The original is lost. It was written in Dutch, and the Latin version which appears in the O.P. may have been made by Spinoza. The Dutch edition has what appears to be a re-translation from the Latin.]

Your last letter, written, if I am not mistaken, on the 26th of last month, has reached me safely. It caused me no little sorrow and anxiety, though that has much diminished when I reflect on the good sense and strength of character which enable you to scorn the adversities of fortune, or what is thought of as such, at the very time when they are assailing you with their strongest weapons. Still, my anxiety increases day by day, and I therefore beg and beseech you not to regard it as burdensome to write to me without stint.

As for the omens which you mention, namely, that while your child was still well and strong you heard groans such as he uttered when he was ill and just before he died, I am inclined to think that these were not real groans but only your imagination; for you say that when you sat up and listened intently you did not hear them as clearly as before, or as later on when you had gone back to sleep. Surely this shows that these groans were no more than mere imagination which, when it was free and unfettered, could imagine definite groans more effectively and vividly than when you sat up to listen in a particular direction. I can confirm, and at the same time explain, what I am here saying by something that happened to me in Rijnsburg last winter.⁶⁰ When one morning just at dawn I awoke from a very deep dream, the images which had come to me in the dream were present before my eyes as vividly as if they had been real things, in particular the image of a black, scabby Brazilian whom I had never seen before. This image disappeared for the most part when, to make a diversion, I fixed my gaze on a book or some other object; but as soon as I again turned my eyes away from such an object while gazing at nothing in particular, the same image of the same Ethiopian kept appearing with the same vividness again and again until it gradually disappeared from sight.

I say that what happened to me in respect of my internal sense of sight happened to you in respect of hearing. But since the cause was quite different, your case was an omen, while mine was not. What I am now going to tell you will make the matter clearly intelligible.

The effects of the imagination arise from the constitution either of body or of mind. To avoid all prolixity, for the present I shall prove this simply from what we experience. We find by experience that fevers and other corporeal changes are the cause of delirium, and that those whose blood is thick imagine nothing but quarrels, troubles, murders and things of that sort. We also see that the imagination can be determined simply by the constitution of the soul, since, as we find, it follows in the wake of the intellect in all things, linking together and interconnecting its images and words just as the intellect does its demonstrations, so that there is almost nothing we can understand without the imagination instantly forming an image.

This being so, I say that none of the effects of the imagination which are due to corporeal causes can ever be omens of things to come, because their causes do not involve any future things. But the effects of imagination, or images, which have their origin in the constitution of the mind can be omens of some future event because the mind can have a confused awareness beforehand of something that is to come. So it can imagine it as firmly and vividly as if such a thing were present to it.

For instance (to take an example like your case), a father so loves his son that he and his beloved son are, as it were, one and the same. And since (as I have demonstrated on another occasion)⁶¹ there must necessarily exist in Thought an idea of the affections of the essence of the son and what follows therefrom, and the father by reason of his union with his son is a part of the said son, the soul of the father must likewise participate in the ideal essence of his son, and in its affections and in what follows therefrom, as I have elsewhere demonstrated at some length. Further, since the soul of the father participates ideally in the things that follow from the essence of the son, he can, as I have said, sometimes imagine something from what follows on the essence of the son as vividly as if he had it in front of him—that is, if the following conditions are fulfilled: (1) If the event which is to happen in the course of the son’s life is one of importance. (2) If it is such as we can quite easily imagine. (3) If the time at which this event will take place is not very remote. (4) Finally, if his body is in good order not only as regards health, but is also free and devoid of all the cares and worries that disturb the senses from without. It could also serve to promote this end if we are thinking of things which especially arouse ideas similar to these. For example, if while conversing with any person we hear groans, it will generally happen that when we again think of that same man, the groans which we heard while speaking to him are likely to come back to mind. This dear friend, is my opinion on the question that you raise. I have been very brief, I confess, but deliberately so, in order to give you material for writing to me at the first opportunity, etc.

LETTER 18
To the esteemed B.d.S., from Willem van Blyenbergh

[Known only from the O.P. The original, which is lost, was written in Dutch, but may be what is in the Dutch edition of the O.P. The Latin is a translation from the Dutch.]

I have now several times had the privilege of perusing your recently published Treatise with its Appendix,⁶² giving it close attention. It would be more seemly to tell others rather than yourself of the great solidity I found there, and the satisfaction it gave me. But I cannot refrain from saying this much, that the more frequently I peruse it with attention, the more it pleases me, and I am continually finding something that I had not noticed before. However, lest in this letter I appear a flatterer, I will not express too much admiration for the author; I know what price in toil the gods demand for all they give.

But not to keep you too long wondering who it is and how it happens that a stranger should assume the great liberty of writing to you, I will tell you that it is one who, impelled only by desire for pure truth, strives in this brief and transitory life to set his feet on the path to knowledge, so far as our human intelligence permits; one who in his search for truth has no other aim than truth itself; one who seeks to acquire for himself through science neither honours nor riches but truth alone, and the peace of mind that results from truth; one who among all truths and sciences takes pleasure in none more than metaphysical studies—if not in all of them, at least in some part of them—and finds all his pleasure in life in devoting thereto all the leisure hours that can be spared. But not everyone is as blessed as you, and not everyone applies himself as diligently as I imagine you have done, and therefore not everyone has attained the degree of perfection which I see from your work you have attained. In a word, it is one whom you would get to know more closely if you would graciously oblige him so very much as to help open a way and pierce through the tangle of his thoughts.

But to return to the Treatise. Just as I found therein many things which appealed very much to my taste, so I also encountered some things which I found difficult to digest. It would not be right for me, a stranger to you, to raise these matters, the more so because I do not know whether or not this would be acceptable to you. That is why I am sending this preliminary letter, with the request that, if in these winter evenings you have the time and the inclination to oblige me so much as to reply to the difficulties which I still find in your book, I may be permitted to send you some of them. But I adjure you not to be hindered thereby from any more necessary or more agreeable pursuit; for I desire nothing more eagerly than the fulfillment of the promise made in your book,⁶³ the fuller explication and publication of your views. What I am now at last entrusting to pen and paper I would rather have put to you in person on greeting you; but because first of all I did not know your address, and then the epidemic and finally my own duties prevented me, this was put off time after time.

But in order that this letter may not be entirely without content, and in the hope that you will not find this unwelcome, I shall raise only this one point. In several places both in the Principia⁶⁴ and in the Cogitata Metaphysica,⁶⁵ in explaining either your own opinion or Descartes’, whose philosophy you were expounding, you maintain that to create and to preserve are one and the same thing (which is so self-evident to those who have turned their minds to it that it is a fundamental notion) and that God has created not only substances but the motions in substances; that is, that God not only preserves substances in their state by a continuous creation but also their motion and their striving. For instance, God, through his immediate will or action (whichever you like to call it), not only brings it about that the soul continues to exist and perseveres in its state, but is also related in the same way to the motion of the soul. That is, just as God’s continuous creation brings it about that things go on existing, so also the striving and motion of things is due to the same cause, since outside God there is no cause of motion. Therefore it follows that God is not only the cause of the substance of the mind but also of every striving or motion of the mind, which we call the will, as you everywhere maintain. From this statement it also seems to follow necessarily either that there is no evil in the motion or will of the soul or that God himself is the immediate agent of that evil. For those things that we call evil also come about through the soul, and consequently through this kind of immediate influence and concurrence of God.

For example, the soul of Adam wants to eat of the forbidden fruit. According to the above statements, it is through God’s influence that not only does Adam will, but also (as will immediately be shown) that he wills thus. So either Adam’s forbidden act, insofar as God not only moved his will but also insofar as he moved it in a particular way, is not evil in itself, or else God himself seems to bring about what we call evil. And it seems to me that neither you nor Monsieur Descartes solve this difficulty by saying that evil is a non-being with which God does not concur.⁶⁶ For whence, then, did the will to eat come, or the Devil’s will to pride? Since the will, as you rightly observe, is not anything different from the mind, but is this or that motion or striving of the mind, it has as much need of God’s concurrence for the one motion as for the other. Now God’s concurrence, as I understand from your writings, is nothing but the determining of a thing by his will in this or that manner. It therefore follows that God concurs with, that is, determines, the evil will insofar as it is evil no less than the good will. For the will of God, which is the absolute cause of all things that exist both in substance and in its strivings, seems to be the prime cause of the evil will insofar as it is evil.

Again, there occurs no determination of will in us without God’s having known it from eternity; otherwise, if he did not know it, we are ascribing imperfection to God. But how could God have known it except through his decrees? So his decrees are the cause of our determinations, and thus it once again seems to follow that either the evil will is not anything evil or that God is the immediate cause of that evil.

And here the Theologians’ distinction regarding the difference between the act and the evil adhering to the act has no validity. For God decreed not only the act but also the manner of the act; that is, God decreed not only that Adam should eat, but also that he necessarily ate contrary to command, so that it again seems to follow that either Adam’s eating the apple contrary to command is no evil, or that God himself wrought that evil.

This much in your Treatise, esteemed Sir, is for the present incomprehensible to me; for the extremes on both sides are hard to maintain. But I expect from your penetrating judgment and diligence a reply that will satisfy me, and I hope to show you in the future how much I shall be obligated to you thereby.

Be assured, esteemed Sir, that my questions are prompted only by zeal for truth, and for no other personal interest. For I am a free person, not dependent on any profession, supporting myself by honest trading and devoting my spare time to these matters. I also humbly ask that my difficulties should not be unwelcome to you; and if you are minded to reply, as is my heartfelt desire, please write to W.v.B., etc.

LETTER 19
To the learned and sagacious Willem van Blyenbergh, from B.d.S.

[Known only from the O.P. The original, which is lost, was written in Dutch, but may be printed in the Dutch edition of the O.P. The Latin is a translation from the Dutch, perhaps by Spinoza. The last paragraph appears only in the Dutch edition.]

Your letter of the 12th December, enclosed in another letter dated the 21st of the same month, I finally received on the 26th of that month while at Schiedam. I gathered from it that you are deeply devoted to truth, which you make the sole aim of all your endeavours. Since I have exactly the same objective, this has determined me not only to grant without stint your request to answer to the best of my ability the questions which you are now sending me and will send me in the future, but also to do everything in my power conducive to further acquaintance and sincere friendship. For my part, of all things that are not under my control, what I most value is to enter into a bond of friendship with sincere lovers of truth. For I believe that such a loving relationship affords us a serenity surpassing any other boon in the whole wide world. The love that such men bear to one another, grounded as it is in the love that each has for knowledge of truth, is as unshakable as is the acceptance of truth once it has been perceived. It is, moreover, the highest source of happiness to be found in things not under our command, for truth more than anything else has the power to effect a close union between different sentiments and dispositions. I say nothing of the considerable advantages that derive therefrom, not wishing to detain you any longer on a matter on which you need no instruction. This much I have said so that you may better understand how pleased I am, and shall continue to be, to have the opportunity of serving you.

To avail myself of the present opportunity, I shall now go on to answer your question. This seems to hinge on the following point, that it seems clearly to follow, both from God’s providence, which is identical with his will, and from God’s concurrence and the continuous creation of things, either that there is no such thing as sin or evil, or that God brings about that sin and that evil. But you do not explain what you mean by evil, and as far as one can gather from the example of Adam’s determinate will, by evil you seem to mean the will itself insofar as it is conceived as determined in a particular way, or insofar as it is in opposition to God’s command. So you say it is quite absurd (and I would agree, if the case were as you say) to maintain either of the following alternatives, that God himself brings to pass what is contrary to his will, or else that what is opposed to God’s will can nevertheless be good. For my own part, I cannot concede that sin and evil are anything positive, much less than anything can be or come to pass against God’s will. On the contrary, I not only assert that sin is not anything positive; I maintain that it is only by speaking improperly or in merely human fashion that we say that we sin against God, as in the expression that men make God angry.⁶⁷

For as to the first point, we know that whatever is, when considered in itself without regard to anything else, possesses a perfection coextensive in every case with the thing’s essence; for its essence is not the same thing. I take as an example Adam’s resolve or determinate will to eat of the forbidden fruit. This resolve or determinate will, considered solely in itself, contains in itself perfection to the degree that it expresses reality. This can be inferred from the fact that we cannot conceive imperfection in things except by having regard to other things possessing more reality.⁶⁸ For this reason, when we consider Adam’s decision in itself without comparing it with other things more perfect or displaying a more perfect state, we cannot find any imperfection in it. Indeed, we may compare it with innumerable other things much more lacking in perfection in comparison with it, such as stones, logs, and so forth. In actual practise, too, this is universally conceded. For everybody beholds with admiration in animals what he dislikes and regards with aversion in men, like the warring of bees, the jealousy of doves, and so on. In men such things are detested, yet we esteem animals as more perfect because of them. This being the case, it clearly follows that sin, since it indicates only imperfection, cannot consist in anything that expresses reality, such as Adam’s decision and its execution.

Furthermore, neither can we say that Adam’s will was at variance with God’s law, and was evil because it was displeasing to God. It would argue great imperfection in God if anything happened against his will, or if he wanted something he could not possess, or if his nature were determined in such a manner that, just like his creatures, he felt sympathy with some things and antipathy to others. Furthermore, this would be in complete contradiction to the nature of God’s will; for since his will is identical with his intellect, it would be just as impossible for anything to take place in opposition to his will as in opposition to his intellect. That is to say, anything that would take place against his will would have to be of such a nature as likewise to be in opposition to his intellect, as, for example, a round square. Therefore since Adam’s will or decision, regarded in itself, was neither evil nor yet, properly speaking, against God’s will, it follows that God can be—or rather, according to the reasoning you refer to, must be—the cause of it. But not insofar as it was evil, for the evil that was in it was simply the privation of a more perfect state which Adam was bound to lose because of his action.

Now it is certain that privation is not something positive, and is so termed in respect of our intellect, not God’s intellect. This is due to the fact that we express by one and the same definition all the individual instances of the same genus—for instance, all that have the outward appearance of men—and we therefore deem them all equally capable of the highest degree of perfection that can be inferred from that particular definition. Now when we find one thing whose actions are at variance with that perfection, we consider that it is deprived of that perfection and is astray from its own nature. This we would not do if we had not referred the individual to that particular definition and ascribed to it such a nature. Now God does not know things in abstraction, nor does he formulate general definitions of that sort, and things possess no more reality than that with which God’s intellect and potency have endowed them, and which he has assigned to them in actual fact. From this it clearly follows that the privation in question is a term applicable in respect of our intellect only, and not of God’s.

This, I believe, is a complete answer to the question. However, to make the path smoother and to remove every shadow of doubt, I think I ought still to answer the following two questions: First, why does Holy Scripture say that God requires the wicked to turn from their evil ways, and why, too, did he forbid Adam to eat of the fruit of the tree when he had ordained the contrary? Secondly, it seems to follow from what I have said that the wicked serve God by their pride, greed and desperate deeds no less than the good by their nobleness, patience, love, etc. For they, too, carry out God’s will.

In reply to the first question, I say that Scripture, being particularly adapted to the needs of the common people, continually speaks in merely human fashion, for the common people are incapable of understanding higher things. That is why I think that all that God has revealed to the Prophets as necessary for salvation is set down in the form of law, and in this way the Prophets made up a whole parable depicting God as a king and lawgiver, because he had revealed the means that lead to salvation and perdition, and was the cause thereof. These means, which are simply causes, they called laws, and wrote them down in the form of laws; salvation and perdition, which are simply effects necessarily resulting from these means, they represented as reward and punishment. All their words were adjusted to the framework of this parable rather than to truth. They constantly depicted God in human form, sometimes angry, sometimes merciful, now looking to what is to come, now jealous and suspicious, and even deceived by the Devil. So philosophers and likewise all who have risen to a level beyond law, that is, all who pursue virtue not as a law but because they love it as something very precious, should not find such words a stumbling-block.

Therefore the command given to Adam consisted solely in this, that God revealed to Adam that eating of that tree brought about death, in the same way that he also reveals to us through our natural understanding that poison is deadly. If you ask to what end he made this revelation, I answer that his purpose was to make Adam that much more perfect in knowledge. So to ask God why he did not give Adam a more perfect will is no less absurd than to ask why he has not bestowed on a circle all the properties of a sphere, as clearly follows from what I have said above, and as I have demonstrated in the Scholium to Proposition 15 of my Principles of Cartesian Philosophy Demonstrated in Geometrical Form, Part 1.

As to the second difficulty, it is indeed true that the wicked express God’s will in their own way, but they are not for that reason at all comparable with the good; for the more perfection a thing has, the more it participates in Deity, and the more it expresses God’s perfection. Since, then, the good have incomparably more perfection than the wicked, their virtue cannot be compared with the virtue of the wicked, because the wicked lack the love of God that flows from the knowledge of God, and by which alone, within the limits of our human intellect, we are said to be servants of God. Indeed, not knowing God, the wicked are but an instrument in the hands of the Maker, serving unconsciously and being used up in that service, whereas the good serve consciously, and in serving become more perfect.

This, Sir, is all I can now put forward in answer to your question. I desire nothing more than that it may satisfy you. But if you still find any difficulty, I beg you to let me know, to see if I can remove it. You on your side need have no hesitation, but as long as you think you are not satisfied, I would like nothing better than to know the reasons for it, so that truth may finally come to light. I would have preferred to write in the language⁶⁹ in which I was brought up; I might perhaps express my thoughts better. But please excuse this, and correct the mistakes yourself, and consider me,

I shall be staying at this Orchard for another three or four weeks, and then I intend to return to Voorburg. I believe I shall receive an answer from you before then, but if your affairs do not permit it, please write to Voorburg with this address—to be delivered to Church Lane at the house of Mr. Daniel Tydeman, painter.

LETTER 20
To the esteemed B.d.S., from Willem van Blyenbergh

[This letter was written in Dutch. The original is extant. The Latin version in the O.P. is a translation from the Dutch.]

When first I received your letter and read it through hastily, I intended not only to reply at once but also to make many criticisms. But the more I read it, the less matter I found to object to; and great as had been my longing to see it, so great was my pleasure in reading it.

But before I proceed to ask you to resolve certain further difficulties for me, you should first know that there are two general rules which always govern my endeavours to philosophise. One is the clear and distinct conception of my intellect, the other is the revealed Word, or will, of God. In accordance with the one, I try to be a lover of truth, while in accordance with both I try to be a Christian philosopher. And whenever it happens that after long consideration my natural knowledge seems either to be at variance with this Word or not very easily reconcilable with it, this Word has so much authority with me that I prefer to cast doubt on the conceptions I imagine to be clear rather than to set these above and in opposition to the truth which I believe I find prescribed for me in that book. And little wonder, since I wish to continue steadfast in the belief that that Word is the Word of God, that is, that it has proceeded from the highest and most perfect God who possesses far more perfection than I can conceive, and who has perhaps willed to predicate of himself and his works more perfection than I with my finite intellect can today perceive. I say ‘can today perceive’, because it is possible that by my own doing I have deprived myself of greater perfection, and so if perchance I were in possession of the perfection whereof I have been deprived by my own doing, I might realise that everything presented and taught to us in that Word is in agreement with the soundest conceptions of my mind. But since I now suspect myself of having by continual error deprived myself of a better state, and since you assert in Principia, Part 1, Proposition 15 that our knowledge, even when most clear, still contains imperfection, I prefer to turn to that Word even without reason, simply on the grounds that it has proceeded from the most perfect Being (I take this for granted at present, since its proof would here be inappropriate or would take too long) and therefore must be accepted by me.

If I were now to pass judgment on your letter solely under the guidance of my first rule, excluding the second rule as if I did not have it or as if it did not exist, I should have to agree with a great deal of it, as indeed I do, and admire your subtle conceptions; but my second rule causes me to differ more widely from you. However, within the limits of a letter, I shall examine them somewhat more extensively under the guidance of both the rules.

First of all, in accordance with the first stated rule, I asked whether, taking into account your assertions that creation and preservation are one and the same thing and that God causes not only things, but the motions and modes of things, to persist in their state (that is, concurs with them) it does not seem to follow that there is no evil or else that God himself brings about that evil. I was relying on the rule that nothing can come to pass against God’s will, since otherwise it would involve an imperfection; or else the things that God brings about, among which seem to be included those we call evil, would also have to be evil. But since this too involves a contradiction, and however I turned it I could not avoid a contradiction, I therefore had recourse to you, who should be the best interpreter of your own conceptions.

In reply you say that you persist in your first presupposition, namely, that nothing happens or can happen against God’s will. But when an answer was required to this problem, whether God then does not do evil, you say that sin is not anything positive, adding that only very improperly can we be said to sin against God. And in the Appendix, Part 1, Chapter 6 you say that there is no absolute evil, as is self-evident; for whatever exists, considered in itself without relation to anything else, possesses perfection, which in every case is co-extensive with the thing’s essence. Therefore it clearly follows that sins, inasmuch as they denote nothing but imperfections, cannot consist in anything that expresses essence. If sin, evil, error, or whatever name one chooses to give it, is nothing else but the loss or deprivation of a more perfect state, then of course it seems to follow that to exist is indeed not an evil or imperfection, but that some evil can arise in an existing thing. For that which is perfect will not be deprived of a more perfect state through an equally perfect action, but through our inclination towards something imperfect because we misuse the powers granted us. This you seem to call not evil, but merely a lesser good, because things considered in themselves contain perfection, and secondly because, as you say, no more essence belongs to things than the divine intellect and power assigns to them and gives them in actual fact, and therefore they can display no more existence in their actions than they have received essence. For if the actions I produce can be no greater or lesser than the essence I have received, it cannot be imagined that there is a privation of a more perfect state. If nothing comes to pass contrary to God’s will, and if what comes to pass is governed by the amount of essence granted, in what conceivable way can there be evil, which you call privation of a better state? How can anyone suffer the loss of a more perfect state through an act thus constituted and dependent? Thus it seems to me that you must maintain one of two alternatives: either that there is some evil, or, if not, that there can be no privation of a better state. For that there is no evil, and that there is privation of a better state, seem to be contradictory.

But you will say that, through privation of a more perfect state, we fall back into a lesser good, not into an absolute evil. But you have taught me (Appendix, Part 1, Chapter 3) that one must not quarrel over words. Therefore I am not now arguing as to whether or not it should be called an absolute evil, but whether the decline from a better to a worse state is not called by us, and ought rightly to be called, a worse state, or a state that is evil. But, you will reply, this evil state yet contains much good. Still, I ask whether that man who through his own folly has been the cause of his own deprivation of a more perfect state and is consequently now less than he was before, cannot be called evil.

To escape from the foregoing chain of reasoning since it still confronts you with some difficulties, you assert that evil does indeed exist, and there was evil in Adam, but it is not something positive, and is called evil in relation to our intellect, not to God’s intellect. In relation to our intellect it is privation (but only insofar as we thereby deprive ourselves of the best freedom which belongs to our nature and is within our power), but in relation to God it is negation.

But let us here examine whether what you call evil, if it were evil only in relation to us, would be no evil; and next, whether evil, taken in the sense you maintain, ought to be called mere negation in relation to God.

The first question I think I have answered to some extent in what I have already said. And although I conceded that my being less perfect than another being cannot posit any evil in me because I cannot demand from my Creator a better state, and that it causes my state to differ only in degree, nevertheless I cannot on that account concede that, if I am now less perfect than I was before and have brought this imperfection on myself through my own fault, I am not to that extent the worse. If, I say, I consider myself as I was before ever I lapsed into imperfection and compare myself with others who possess a greater perfection than I, that lesser perfection is not an evil but a lower grade of good. But if, after falling from a more perfect state and being deprived thereof by my own folly, I compare myself with my original more perfect condition with which I issued from the hand of my Creator, I have to judge myself to be worse than before. For it is not my Creator, but I myself, who has brought me to this pass. I had power enough, as you yourself admit, to preserve myself from error.

To come to the second question, namely, whether the evil which you maintain consists in the privation of a better state—which not only Adam but all of us have lost through rash and ill-considered action—whether this evil, I say, is in relation to God a mere negation. Now to submit this to a thorough examination, we must see how you envisage man and his dependency on God prior to any error, and how you envisage the same man after error. Before error you depict him as possessing no more essence than the divine intellect and power has assigned to him and in actual fact bestows on him. That is, unless I mistake your meaning, man can possess no more and no less perfection than is the essence with which God has endowed him; that is to say, you make man dependent on God in the same way as elements, stones, plants, etc. But if that is your opinion, I fail to understand the meaning of Principia, Part 1, Proposition 15 where you say, “Since the will is free to determine itself, it follows that we have the power of restraining our faculty of assent within the limits of the intellect, and therefore of bringing it about that we do not fall into error.” Does it not seem a contradiction to make the will so free that it can keep itself from error, and at the same time to make it so dependent on God that it cannot manifest either more or less perfection than God has given it essence?

As to the other question, namely, how you envisage man after error, you say that man deprives himself of a more perfect state by an over-hasty action, namely, by not restraining his will within the limits of his intellect. But it seems to me that both here and in the Principia you should have shown in more detail the two extremes of this privation, what he possessed before the privation and what he still retained after the loss of that perfect state, as you call it. There is indeed something said about what we have lost, but not about what we have retained, in Principia, Part 1, Proposition 15: So the whole imperfection of error consists solely in the privation of the best freedom, which is called error. Let us take a look at these two statements just as they are set out by you. You maintain not only that there are in us such very different modes of thinking, some of which we call willing and others understanding, but also that their proper ordering is such that we ought not to will things before we clearly understand them. You also assert that if we restrain our will within the limits of our intellect we shall never err, and, finally, that it is within our power to restrain the will within the limits of the intellect.

When I give earnest consideration to this, surely one of two things must be true: either all that has been asserted is mere fancy, or God has implanted in us this same order. If he has so implanted it, would it not be absurd to say that this has been done to no purpose, and that God does not require us to observe and follow this order? For that would posit a contradiction in God. And if we must observe the order implanted in us, how can we then be and remain thus dependent on God? For if no one shows either more or less perfection than he has received essence, and if this power must be known by its effects, he who lets his will extend beyond the limits of his intellect has not received sufficient power from God; otherwise he would also have put it into effect. Consequently, he who errs has not received from God the perfection of not erring; if he had, he would not have erred. For according to you there is always as much of essence given us as there is of perfection realised.

Secondly, if God has assigned us as much essence as enables us to observe that order, as you assert we are able to do, and if we always produce as much perfection as we possess essence, how comes it that we transgress that order? How comes it that we are able to transgress that order and that we do not always restrain the will within the limits of the intellect?

Thirdly, if, as I have already shown you to assert, I am so dependent on God that I cannot restrain my will either within or beyond the limits of my intellect unless God has previously given me so much essence and, by his will, has predetermined the one course or the other, how then, if the matter be deeply considered, can freedom of will be available to me? Does it not seem to argue a contradiction in God, to lay down an order for restraining our will within the limits of our intellect, and not to vouchsafe us as much essence or perfection as to enable us to observe that order? And if, in accordance with your opinion, he has granted us that much perfection, we surely could never have erred. For we must produce as much perfection as we possess essence, and always manifest in our actions the power granted us. But our errors are a proof that we do not possess a power of the kind that is thus dependent on God, as you hold. So one of these alternatives must be true: either we are not dependent on God in that way, or we do not have in ourselves the power of being able not to err. But on your view we do have the power not to err. Therefore we cannot be dependent on God in that way.

From what has been said I think it is now clear that it is impossible that evil, or being deprived of a better state, should be a negation in relation to God. For what is meant by privation, or the loss of a more perfect state? Is it not to pass from a greater to a lesser perfection, and consequently from a greater to a lesser essence, and to be placed by God in a certain degree of perfection and essence? Is that not to will that we can acquire no other state outside his perfect knowledge, unless he had decreed and willed otherwise? Is it possible that this creature, produced by that omniscient and perfect Being who willed that it should retain a certain state of essence—indeed, a creature with whom God continually concurs so as to maintain it in that state—that this creature should decline in essence, that is, should be diminished in perfection, without God’s knowledge? This seems to involve an absurdity. Is it not absurd to say that Adam lost a more perfect state and was consequently incapable of practising the order which God had implanted in his soul, while God had no knowledge of that loss and of that imperfection? Is it conceivable that God should constitute a being so dependent that it would produce just such an action and then should lose a more perfect state because of that action (of which God, moreover, would be an absolute cause), and yet God would have no knowledge of it?

I grant that there is a difference between the act and the evil adhering to the act; but that ‘evil in relation to God is negation’ is beyond my comprehension. That God should know the act, determine it and concur with it, and yet have no knowledge of the evil that is in the act nor of its outcome—this seems to me impossible in God.

Consider with me that God concurs with my act of procreation with my wife; for that is something positive, and consequently God has clear knowledge of it. But insofar as I misuse this act with another woman contrary to my promise and vow, evil accompanies the act. What could be negative here in relation to God? Not the act of procreation; for insofar as that is positive, God concurs with it. Therefore the evil that accompanies the act must be only that, contrary to my own pledge or God’s command, I do this with a woman with whom this is not permissible. Now is it conceivable that God should know our actions and concur with them, and yet not know with whom we engage in those actions—especially since God also concurs with the action of the woman with whom I transgressed? It seems hard to think this of God.

Consider the act of killing. Insofar as it is a positive act, God concurs with it. But the result of that action, namely, the destruction of a being and the dissolution of God’s creature—would God be unaware of this, as if his own work could be unknown to him? (I fear that here I do not properly understand your meaning, for you seem to me too subtle a thinker to perpetrate so gross an error.) Perhaps you will reply that those actions, just as I present them, are all simply good, and that no evil accompanies them. But then I cannot understand what it is you call evil, which follows on the privation of a more perfect state; and furthermore the whole world would then be put in eternal and lasting confusion, and we men would become beasts. Consider, I pray, what profit this opinion would bring to the world.

You also reject the common description of man, and you attribute to each man as much perfection of action as God has in fact bestowed on him to exercise. But this way of thinking seems to me to imply that the wicked serve God by their works just as well as do the godly. Why? Because neither of them can perform actions more perfect than they have been given essence, and which they show in what they practise. Nor do I think that you give a satisfactory reply to my question in your second answer, where you say:—The more perfection a thing has, the more it participates in Deity, and the more it expresses God’s perfection. Therefore since the good have incalculably more perfection than the wicked, their virtue cannot be compared with that of the wicked. For the latter are but a tool in the hands of the master, which serves unconsciously and is consumed in serving. But the good serve consciously, and in serving become more perfect. In both cases, however, this much is true—they can do no more; for the more perfection the one displays compared with the other, the more essence he has received compared with the other. Do not the godless with their small store of perfection serve God equally as well as the godly? For according to you God demands nothing more of the godless; otherwise he would have granted them more essence. But he has not given them more essence, as is evident from their works. Therefore he asks no more of them. And if it is the case that each of them after his kind does what God wills, neither more nor less, why should he whose achievement is slight, yet as much as God demands of him, not be equally acceptable to God as the godly?

Furthermore, as according to you we lose a more perfect state by our own folly through the evil that accompanies the act, so here too you appear to assert that by restraining the will within the limits of the intellect we not only preserve our present perfection but we even become more perfect by serving. I believe there is a contradiction here, if we are so dependent on God as to be unable to produce either more or less perfection than we have received essence—that is, than God has willed—and yet we should become worse through our folly, or better through our prudence. So if man is such as you describe him, you seem to be maintaining nothing other than this, that the ungodly serve God by their works just as much as the godly by their works, and in this way we are made as dependent on God as elements, plants, stones, etc. Then what purpose will our intellect serve? What purpose the power to restrain the will within the limits of the intellect? Why has that order been imprinted in us?

And see, on the other side, what we deprive ourselves of, namely, painstaking and earnest deliberation as to how we may render ourselves perfect in accordance with the rule of God’s perfection and the order implanted in us. We deprive ourselves of the prayer and yearnings towards God wherefrom we perceive we have so often derived a wonderful strength. We deprive ourselves of all religion, and all the hope and comfort we expect from prayer and religion. For surely if God has no knowledge of evil, it is still less credible that he will punish evil. What reasons can I have, then, for not eagerly committing all sorts of villainy (provided I can escape the judge)? Why not enrich myself by abominable means? Why not indiscriminately do whatever I like, according to the promptings of the flesh? You will say, because virtue is to be loved for itself. But how can I love virtue? I have not been given that much essence and perfection. And if I can gain just as much contentment from the one course as the other, why force myself to restrain the will within the limits of the intellect? Why not do what my passions suggest? Why not secretly kill the man who gets in my way? See what an opportunity we give to all the ungodly, and to godlessness. We make ourselves just like logs, and all our actions like the movements of a clock.

From what has been said it seems to me very hard to maintain that only improperly can we be said to sin against God. For then what is the significance of the power granted to us to restrain the will within the limits of the intellect, by transgressing which we sin against that order? Perhaps you will reply, this is not a case of sinning against God, but against ourselves; for if it could properly be said that we sin against God, it must also be said that something happens against God’s will, which according to you is an impossibility, and therefore so is sinning. Still, one of these alternatives must be true: either God wills it, or he does not. If God will its, how can it be evil in respect to us? If he does not will it, on your view it would not come to pass. But although this, on your view, would involve some absurdity, nevertheless it seems to me very dangerous to admit therefore all the absurdities already stated. Who knows whether, by careful thought, a remedy may not be found to effect some measure of reconciliation?

With this I bring to an end my examination of your letter in accordance with my first general rule. But before proceeding to examine it according to the second rule, I have yet two points to make which are relevant to the line of thought of your letter, both set forth in your Principia, Part 1, Proposition 15. First, you affirm that ‘we can keep the power of willing and judging within the limits of the intellect’. To this I cannot give unqualified agreement. For if this were true, surely out of countless numbers at least one man would be found who would show by his actions that he had this power. Now everyone can discover in his own case that, however much strength he exerts, he cannot attain this goal. And if anyone has any doubt about this, let him examine himself and see how often, in despite of his intellect, his passions master his reason even when he strives with all his might.

But you will say that the reason we do not succeed is not because it is impossible, but because we do not apply enough diligence. I reply that if it were possible, then at least there would be one instance found out of so many thousands. But from all men there has not been, nor is there, one who would venture to boast that he has never fallen into error. What surer arguments than actual examples could be adduced to prove this point? Even if there were just a few, then there would be at least one to be found; but since there is not a single one, then likewise there is no proof.

But you will persist and say: if it is possible that, by suspending judgment and restraining the will within the bounds of the intellect, I can once bring it about that I do not err, why could I not always achieve this by applying the same diligence? I reply that I cannot see that we have this day as much strength as enables us to continue so always. On one occasion, by putting all my effort into it, I can cover two leagues in one hour; but I cannot always manage that. Similarly on one occasion I can by great exertion keep myself from error, but I do not always have the strength to accomplish this. It seems clear to me that the first man, coming forth from the hand of that perfect craftsman, did have that power; but (and in this I agree with you) either by not making sufficient use of that power or by misusing it, he lost his perfect state of being able to do what had previously been within his power. This I could confirm by many arguments, were it not too lengthy a business. And in this I think lies the whole essence of Holy Scripture, which we ought therefore to hold in high esteem, since it teaches us what is so clearly confirmed by our natural understanding, that our fall from our first perfection was due to our folly. What then is more essential than to recover from that fall as far as we can? And that is also the sole aim of Holy Scripture, to bring fallen man back to God.

The second point from the Principia, Part 1, Proposition 15 affirms that to understand things clearly and distinctly is contrary to the nature of man, from which you finally conclude that it is far better to assent to things even though they are confused, and to exercise our freedom, than to remain for ever indifferent, that is, at the lowest degree of freedom. I do not find this clear enough to win my assent. For suspension of judgment preserves us in the state in which we were created by our Creator, whereas to assent to what is confused is to assent to what we do not understand, and thus to give equally ready assent to the false as to the true. And if (as Monsieur Descartes somewhere teaches us)⁷⁰ we do not in assenting comply with that order which God has given us in respect of our intellect and will, namely, to withhold assent from what is not clearly perceived, then even though we may chance to hit upon truth, yet we are sinning in not embracing truth according to that order which God has willed. Consequently, just as the withholding of assent preserves us in the state in which we were placed by God, so assenting to things confused puts us in a worse position. For it lays the foundations of error whereby we thereafter lose our perfect state.

But I hear you say, is it not better to render ourselves more perfect by assenting to things even though confused than, by not assenting, to remain always at the lowest degree of perfection and freedom? But apart from the fact that we have denied this and in some measure have shown that we have rendered ourselves not better but worse, it also seems to us an impossibility and practically a contradiction that God should make the knowledge of things determined by himself extend beyond the knowledge that he has given us. Indeed, God would thus contain within himself the absolute cause of our errors. And it is not inconsistent with this that we cannot complain of God that he did not bestow on us more than he has bestowed, since he was not bound so to do. It is indeed true that God was not bound to give us more than he has given us; but God’s supreme perfection also implies that a creature proceeding from him should involve no contradiction, as would then appear to follow. For nowhere in created Nature do we find knowledge other than in our own intellect. To what end could this have been granted us other than that we might contemplate and know God’s works? And what seems to be a more certain conclusion than that there must be agreement between things to be known and our intellect?

But if I were to examine your letter under the guidance of my second general rule, our differences would be greater than under the first rule. For I think (correct me if I am wrong) that you do not ascribe to Holy Scripture that infallible truth and divinity which I believe lies therein. It is indeed true that you declare your belief that God has revealed the things of Holy Scripture to the prophets, but in such an imperfect manner that, if it were as you say, it would imply a contradiction in God. For if God has revealed his Word and his will to men, then he has done so for a definite purpose, and clearly. Now if the prophets have composed a parable out of the Word which they received, then God must either have willed this, or not willed it. If God willed that they should compose a parable out of his Word, that is, that they should depart from his meaning, God would be the cause of that error and would have willed something self-contradictory. If God did not will it, it would have been impossible for the prophets to compose a parable therefrom. Moreover, it seems likely, on the supposition that God gave his Word to the prophets, that he gave it in such a way that they did not err in receiving it. For God must have had a definite purpose in revealing his Word; but his purpose could not have been to lead men into error, thereby, for that would be a contradiction in God. Again, man could not have erred against God’s will, for that is impossible according to you. In addition to all this, it cannot be believed of the most perfect God that he should permit his Word, given to the prophets to communicate to the people, to have a meaning given it by the prophets other than what God willed. For if we maintain that God communicated his Word to the prophets, we thereby maintain that God appeared to the prophets, or spoke with them, in a miraculous way. If now the prophets composed a parable from the communicated Word,—that is, gave it a meaning different from that which God intended them to give—God must have so instructed them. Again, it is as impossible in respect of the prophets as it is contradictory in respect of God, that the prophets could have understood a meaning different from that which God intended.

You also seem to provide scant proof that God revealed his Word in the manner you indicate, namely, that he revealed only salvation and perdition, decreeing the means that would be certain to bring this about, and that salvation and perdition are no more than the effects of the means decreed by him. For surely if the prophets had understood God’s word in that sense, what reasons could they have had for giving it another meaning? But I do not see you produce a single proof to persuade us that we should prefer your view to that of the prophets. If you think your proof to consist in this, that otherwise the Word would include many imperfections and contradictions, I say that this is mere assertion, not proof. And if both meanings were squarely before us, who knows which would contain fewer imperfections? And finally, the supremely perfect Being knew full well what the people could understand, and therefore what must be the best method of instructing them.

As to the second part of your first question, you ask yourself why God forbade Adam to eat of the fruit of the tree when he had nevertheless decreed the contrary; and you answer that the prohibition to Adam consisted only in this, that God revealed to Adam that the eating of the fruit of the tree caused death just as he reveals to us through our natural intellect that poison is deadly for us. If it is established that God forbade something to Adam, what reasons are there why I should give more credence to your account of the manner of the prohibition than to that given by the prophets to whom God himself revealed the manner of the prohibition? You will say that your account of the prohibition is more natural, and therefore more in agreement with truth and more befitting God. But I deny all this. Nor can I conceive that God has revealed to us through our natural understanding that poison is deadly; and I do not see why I would ever know that something is poisonous if I had not seen and heard of the evil effects of poison in others. Daily experience teaches us how many men, not recognising poison, unwittingly eat it and die. You will say that if people knew it was poison, they would realise that it is evil. But I reply that no one knows poison, or can know it, unless he has seen or heard that someone has come to harm by using it. And if we suppose that up to this day we had never heard or seen that someone had done himself harm by using this kind of thing, not only would we be unaware of it now but we would not be afraid to use it, to our detriment. We learn truths of this kind every day.

What in this life can give greater delight to a well-formed intellect than the contemplation of that perfect Deity? For being concerned with that which is most perfect, such contemplation must also involve in itself the highest perfection that can come within the scope of our finite intellect. Indeed, there is nothing in my life for which I would exchange this pleasure. In this I can pass much time in heavenly joy, though at the same time being much distressed when I realise that my finite intellect is so wanting. Still, I soothe this sadness with the hope I have—a hope that is dearer to me than life—that I shall exist hereafter and continue to exist, and shall contemplate that Deity more perfectly than I do today. When I consider this brief and fleeting life in which I look to my death at any moment, if I had to believe that there would be an end of me and I should be cut off from that holy and glorious contemplation, then surely I would be more wretched than all creatures who have no knowledge of their end. For before my death, fear of death would make me wretched, and after my death I would be nothing, and therefore wretched in being deprived of that divine contemplation.

Now it is to this that your opinions seem to lead, that when I cease to be here, I shall for ever cease to be. Against this the Word and will of God, by their inner testimony in my soul, give me assurance that after this life I shall eventually in a more perfect state rejoice in contemplation of the most perfect Deity. Surely, even if that hope should turn out to be false, yet it makes me happy as long as I hope. This is the only thing I ask of God, and shall continue to ask, with prayers, sighs and earnest supplication (would that I could do more to this end!) that as long as there is breath in my body, it may please him of his goodness to make me so fortunate that, when this body is dissolved, I may still remain an intellectual being able to contemplate that most perfect Deity. And if only I obtain that, it matters not to me what men here believe, and what convictions they urge on one another, and whether or not there is something founded on our natural intellect and can be grasped by it. This, and this alone, is my wish, my desire, and my constant prayer, that God should establish this certainty in my soul. And if I have this (and oh! if I have it not, how wretched am I!), then let my soul cry out, “As the hart panteth after the water-brook, so longeth my soul for thee, O living God. O when will come the day when I shall be with thee and behold thee?”⁷¹ If only I attain to that, then have I all the aspiration and desire of my soul. But in your view such hopes are not for me, since our service is not pleasing to God. Nor can I understand why God (if I may speak of him in so human a fashion) should have brought us forth and sustained us, if he takes no pleasure in our service and our praise. But if I have misunderstood your views, I should like to have your clarification.

But I have detained myself, and perhaps you as well, far too long; and seeing that my time and paper are running out, I shall end. These are the points in your letter I would still like to have resolved. Perhaps here and there I have drawn from your letter a conclusion which may chance not to be your own view; but I should like to hear your explanation regarding this.

I have recently occupied myself in reflecting on certain attributes of God, in which your appendix has given me no little help. I have in effect merely paraphrased your views, which seem to me little short of demonstrations. I am therefore very much surprised that L. Meyer says in his Preface that this does not represent your opinions, that you were under an obligation thus to instruct your pupil in Descartes’ philosophy, as you had promised, but that you held very different views both of God and the soul, and in particular the will of the soul. I also see stated in that Preface that you will shortly publish the Cogitata Metaphysica in an expanded form. I very much look forward to both of these, for I have great expectations of them. But it is not my custom to praise someone to his face.

This is written in sincere friendship, as requested in your letter, and to the end that truth may be discovered. Forgive me for having written at greater length than I had intended. If I should receive a reply from you, I should be much obliged to you. As to writing in the language in which you were brought up, I can have no objection, if at least it is Latin or French. But I beg you to let me have your answer in this same language, for I have understood your meaning in it quite well, and perhaps in Latin I should not understand it so clearly. By so doing you will oblige me, so that I shall be, and remain,

In your reply I should like to be informed more fully what you really mean by negation in God.

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TO B.D.S.
AND THE AUTHOR’S REPLIES CONTRIBUTING NOT A LITTLE TO THE ELUCIDATION OF HIS OTHER WORKS

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To the most esteemed B.d.S., from Henry Oldenburg

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To the most noble and learned Henry Oldenburg, from B.d.S. containing comments on the book of the most noble Robert Boyle, on Nitre, Fluidity and Solidity

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2Henry Oldenburg to the esteemed B.d.S.

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THE LETTERSOF CERTAIN LEARNED MENTO B.D.S.AND THE AUTHOR’S REPLIES CONTRIBUTING NOT A LITTLE TO THE ELUCIDATION OF HIS OTHER WORKS

THE LETTERS
OF CERTAIN LEARNED MEN
TO B.D.S.
AND THE AUTHOR’S REPLIES CONTRIBUTING NOT A LITTLE TO THE ELUCIDATION OF HIS OTHER WORKS