The will as thing-in-itself is quite different from its phenomenon, and is entirely free from all the forms of the phenomenon into which it first passes when it appears, and which therefore concern only its objectivity, and are foreign to the will itself. Even the most universal form of all representation, that of object for subject, does not concern it, still less the forms that are subordinate to this and collectively have their common expression in the principle of sufficient reason. As we know, time and space belong to this principle, and consequently plurality as well, which exists and has become possible only through them. In this last respect I shall call time and space the principium individuationis, an expression borrowed from the old scholasticism, and I beg the reader to bear this in mind once and for all. For it is only by means of time and space that something which is one and the same according to its nature and the concept appears as different, as a plurality of coexistent and successive things. Consequently, time and space are the principium individuationis, the subject of so many subtleties and disputes among the scholastics which are found collected in Suarez (Disp. 5, sect. 3). It is apparent from what has been said that the will as thing-in-itself lies outside the province of the principle of sufficient reason in all its forms, and is consequently completely groundless, although each of its phenomena is entirely subject to that principle. Further, it is free from all plurality, although its phenomena in time and space are innumerable. It is itself one, yet not as an object is one, for the unity of an object is known only in contrast to possible plurality. Again, the will is one not as a concept is one, for a concept originates only through abstraction from plurality; but it is one as that which lies outside time and space, outside the principium individuationis, that is to say, outside the possibility of plurality. Only when all this has become quite clear to us through the following consideration of phenomena and of the different manifestations of the will, can we fully understand the meaning of the Kantian doctrine that time, space, and causality do not belong to the thing-in-itself, but are only the forms of our knowing.
The groundlessness of the will has actually been recognized where it manifests itself most distinctly, that is, as the will of man; and this has been called free and independent. But as to the groundlessness of the will itself, the necessity to which its phenomenon is everywhere liable has been overlooked, and actions have been declared to be free, which they are not. For every individual action follows with strict necessity from the effect of the motive on the character. As we have already said, all necessity is the relation of the consequent to the ground, and nothing else whatever. The principle of sufficient reason is the universal form of every phenomenon, and man in his action, like every other phenomenon, must be subordinated to it. But because in self-consciousness the will is known directly and in itself, there also lies in this consciousness the consciousness of freedom. But the fact is overlooked that the individual, the person, is not will as thing-in-itself, but is phenomenon of the will, is as such determined, and has entered the form of the phenomenon, the principle of sufficient reason. Hence we get the strange fact that everyone considers himself to be a priori quite free, even in his individual actions, and imagines he can at any moment enter upon a different way of life, which is equivalent to saying that he can become a different person. But a posteriori through experience, he finds to his astonishment that he is not free, but liable to necessity; that notwithstanding all his resolutions and reflections he does not change his conduct, and that from the beginning to the end of his life he must bear the same character that he himself condemns, and, as it were, must play to the end the part he has taken upon himself. I cannot pursue this discussion any further here, for, being ethical, it belongs to another part of this work. Meanwhile, I wish to point out here only that the phenomenon of the will, in itself groundless, is yet subject as such to the law of necessity, that is to say, to the principle of sufficient reason, so that in the necessity with which the phenomena of nature ensue, we may not find anything to prevent us from recognizing in them the manifestations of the will.
Hitherto we have regarded as phenomena of the will only those changes that have no other ground than a motive, i.e., a representation. Therefore in nature a will has been attributed only to man, or at most to animals, because, as I have already mentioned elsewhere, knowing or representing is of course the genuine and exclusive characteristic of the animal kingdom. But we see at once from the instinct and mechanical skill of animals that the will is also active where it is not guided by any knowledge.59 That they have representations and knowledge is of no account at all here, for the end towards which they work as definitely as if it were a known motive remains entirely unknown to them. Therefore, their action here takes place without motive, is not guided by the representation, and shows us first and most distinctly how the will is active even without any knowledge. The one-year-old bird has no notion of the eggs for which it builds a nest; the young spider has no idea of the prey for which it spins a web; the ant-lion has no notion of the ant for which it digs a cavity for the first time. The larva of the stag-beetle gnaws the hole in the wood, where it will undergo its metamorphosis, twice as large if it is to become a male beetle as if it is to become a female, in order in the former case to have room for the horns, though as yet it has no idea of these. In the actions of such animals the will is obviously at work as in the rest of their activities, but is in blind activity, which is accompanied, indeed, by knowledge, but not guided by it. Now if we have once gained insight into the fact that representation as motive is not a necessary and essential condition of the will’s activity, we shall more easily recognize the action of the will in cases where it is less evident. For example, we shall no more ascribe the house of the snail to a will foreign to the snail itself but guided by knowledge, than we shall say that the house we ourselves build comes into existence through a will other than our own. On the contrary, we shall recognize both houses as works of the will objectifying itself in the two phenomena, working in us on the basis of motives, but in the snail blindly as formative impulse directed outwards. Even in us the same will in many ways acts blindly; as in all those functions of our body which are not guided by knowledge, in all its vital and vegetative processes, digestion, circulation, secretion, growth, and reproduction. Not only the actions of the body, but the whole body itself, as was shown above, is phenomenon of the will, objectified will, concrete will. All that occurs in it must therefore occur through will, though here this will is not guided by knowledge, not determined according to motives, but acts blindly according to causes, called in this case stimuli.
I call cause in the narrowest sense of the word that state or condition of matter which, while it brings about another state with necessity, itself suffers a change just as great as that which it causes. This is expressed by the rule “Action and reaction are equal.” Further, in the case of a cause proper, the effect increases in exact proportion to the cause, and hence the counter-effect or reaction also. Thus, if once the mode of operation is known, the degree of the effect can be measured and calculated from the degree of intensity of the cause, and conversely. Such causes, properly so called, operate in all the phenomena of mechanics, chemistry, and so forth; in short, in all the changes of inorganic bodies. On the other hand, I call stimulus that cause which itself undergoes no reaction proportional to its effect, and whose intensity runs by no means parallel with the intensity of the effect according to degree; so that the effect cannot be measured from it. On the contrary, a small increase of the stimulus may cause a very large increase in the effect, or, conversely may entirely eliminate the previous effect, and so forth. Every effect on organized bodies as such is of this kind. Therefore all really organic and vegetative changes in the animal body take place from stimuli, not from mere causes. But the stimulus, like every cause and motive in general, never determines more than the point of entry of the manifestation of every force in time and space, not the inner nature of the force that manifests itself. According to our previous deduction, we recognize this inner nature to be will, and to this therefore we ascribe both the unconscious and the conscious changes of the body. The stimulus holds the mean, forms the transition, between the motive, which is causality that has passed through knowledge, and the cause in the narrowest sense. In particular cases it is sometimes nearer the motive, sometimes nearer the cause, yet it can always be distinguished from both. Thus, for example. the rising of the sap in plants occurs as a result of stimuli, and cannot be explained from mere causes in accordance with the laws of hydraulics or capillary tubes; yet it is certainly aided by these, and in general it approaches very closely to a purely causal change. On the other hand, the movements of Hedysarum gyrans and Mimosa pudica, though still following on mere stimuli, are very similar to those that follow on motives, and seem almost to want to make the transition. The contraction of the pupil of the eye with increased light occurs on stimulus, but passes over into movement on motive, for it takes place because too strong a light would affect the retina painfully, and to avoid this we contract the pupil. The occasion of an erection is a motive, as it is a representation; yet it operates with the necessity of a stimulus, in other words, it cannot be resisted, but must be put away in order to be made ineffective. This is also the case with disgusting objects which stimulate the desire to vomit. We have just considered the instinct of animals as an actual link of quite a different kind between movement on stimulus and action according to a known motive. We might be tempted to regard respiration as another link of this kind. It has been disputed whether it belongs to the voluntary or the involuntary movements, that is to say, whether it ensues on motive or on stimulus; accordingly, it might possibly be explained as something between the two. Marshall Hall (On the Diseases of the Nervous System, §§ 293 seq.) declares it to be a mixed function, for it is under the influence partly of the cerebral (voluntary), partly of the spinal (involuntary) nerves. However, we must class it ultimately with the manifestations of will following on motive, for other motives, i.e., mere representations, can determine the will to check or accelerate it, and, as with every other voluntary action, it seems that a man might abstain from breathing altogether and freely suffocate. In fact, this could be done the moment some other motive influenced the will so powerfully that it overcame the pressing need for air. According to some, Diogenes is supposed actually to have put an end to his life in this way (Diogenes Laërtius, VI, 76). Negroes also are said to have done this (F. B. Osiander, Über den Selbstmord [1813], pp. 170-180). We might have here a striking example of the influence of abstract motives, i.e., of the superior force of really rational over mere animal willing. That breathing is at any rate in part conditioned by cerebral activity is shown by the fact that prussic acid kills by first of all paralyzing the brain, and hence by indirectly stopping respiration. If, however, the breathing is artificially maintained until the narcotic effect has passed off, death does not occur at all. Incidentally, respiration gives us at the same time the most striking example of the fact that motives act with just as great a necessity as do stimuli and mere causes in the narrowest sense, and that they can be put out of action only by opposite motives, just as pressure is neutralized by counterpressure. For in the case of breathing, the illusion of being able to abstain is incomparably weaker than in the case of other movements that follow on motives, because with breathing the motive is very pressing, very near, its satisfaction is very easy on account of the untiring nature of the muscles that perform it, nothing as a rule opposes it, and the whole process is supported by the most inveterate habit on the part of the individual. And yet all motives really act with the same necessity. The knowledge that necessity is common to movements following on motives and to movements following on stimuli will make it easier for us to understand that even what takes place in the organic body on stimuli and in complete conformity to law is yet, according to its inner nature, will. This will, never of course in itself, but in all its phenomena, is subject to the principle of sufficient reason, in other words to necessity.60 Accordingly, we shall not confine ourselves here to recognizing animals as phenomena of will in their actions as well as in their whole existence, bodily structure, and organization, but shall extend also to plants this immediate knowledge of the inner nature of things that is given to us alone. All the movements of plants follow on stimuli, for the absence of knowledge and of the movement on motives conditioned by such knowledge constitutes the only essential difference between animal and plant. Therefore what appears for the representation as plant, as mere vegetation, as blindly urging force, will be taken by us, according to its inner nature, to be will, and it will be recognized by us as that very thing which constitutes the basis of our own phenomenon, as it expresses itself in our actions, and also in the whole existence of our body itself.
It only remains for us to take the final step, namely that of extending our method of consideration to all those forces in nature which act according to universal, immutable laws, in conformity with which there take place the movements of all those bodies, such bodies being entirely without organs, and having no susceptibility to stimulus and no knowledge of motive. We must therefore also apply the key for an understanding of the inner nature of things, a key that only the immediate knowledge of our own inner nature could give us, to these phenomena of the inorganic world, which are the most remote of all from us. Now let us consider attentively and observe the powerful, irresistible impulse with which masses of water rush downwards, the persistence and determination with which the magnet always turns back to the North Pole, the keen desire with which iron flies to the magnet, the vehemence with which the poles of the electric current strive for reunion, and which, like the vehemence of human desires, is increased by obstacles. Let us look at the crystal being rapidly and suddenly formed with such regularity of configuration; it is obvious that this is only a perfectly definite and precisely determined striving in different directions constrained and held firm by coagulation. Let us observe the choice with which bodies repel and attract one another, unite and separate, when set free in the fluid state and released from the bonds of rigidity. Finally, we feel directly and immediately how a burden, which hampers our body by its gravitation towards the earth, incessantly presses and squeezes this body in pursuit of its one tendency. If we observe all this, it will not cost us a great effort of the imagination to recognize once more our own inner nature, even at so great a distance. It is that which in us pursues its ends by the light of knowledge, but here, in the feeblest of its phenomena, only strives blindly in a dull, one-sided, and unalterable manner. Yet, because it is everywhere one and the same—just as the first morning dawn shares the name of sunlight with the rays of the full midday sun—it must in either case bear the name of will. For this word indicates that which is the being-in-itself of every thing in the world, and is the sole kernel of every phenomenon.
However, the remoteness, in fact the appearance of a complete difference between the phenomena of inorganic nature and the will, perceived by us as the inner reality of our own being, arises principally from the contrast between the wholly determined conformity to law in the one species of phenomenon, and the apparently irregular arbitrariness in the other. For in man individuality stands out powerfully; everyone has a character of his own, and hence the same motive does not have the same influence on all, and a thousand minor circumstances, finding scope in one individual’s wide sphere of knowledge but remaining unknown to others, modify its effect. For this reason an action cannot be predetermined from the motive alone, since the other factor, namely an exact acquaintance with the individual character, and with the knowledge accompanying that character, is wanting. On the other hand, the phenomena of the forces of nature show the other extreme in this respect. They operate according to universal laws, without deviation, without individuality, in accordance with openly manifest circumstances, subject to the most precise predetermination; and the same force of nature manifests itself in its million phenomena in exactly the same way. To explain this point, to demonstrate the identity of the one and indivisible will in all its very varied phenomena, in the feeblest as in the strongest, we must first of all consider the relation between the will as thing-in-itself and its phenomenon, i.e., between the world as will and the world as representation. This will open up for us the best way to a more thorough and searching investigation of the whole subject dealt with in this second book.61