It follows necessarily from the twenty-fifth premise that there is a mover, which has moved the matter of that which is subject to generation and corruption so that it received form. If now it is asked: what moved this proximate mover? — it follows of necessity that there exists for it another mover either of its own species or of a different species; for motion exists in four categories,1 and sometimes these different kinds of change are called motion in a general way, as we have mentioned in the fourth premise. Now this does not go to infinity, as we have mentioned in the third premise. For we have found that every movement goes back, in the last resort, to the movement of the fifth body, and no further. It is from this movement that every mover and predisposer in the whole lower world proceeds and derives. Now the sphere moves with a movement of translation, and this is prior to all other movements, as has been mentioned in the fourteenth premise. Similarly every movement of translation goes back, in the last resort, to the movement of the sphere. It is as if you say: this stone, which was in motion, was moved by a staff; the staff was moved by a hand; the hand by tendons; the tendons by muscles; the muscles by nerves; the nerves by natural heat; and the natural heat by the form that subsists therein, this form being undoubtedly the first mover. What obliges this mover to move could be an opinion, for instance an opinion that the stone should be brought by the blow of the staff [6a] to a hole2 in order to stop it, so that blowing wind should not enter thereby toward the man who had this opinion.3 Now the mover of this wind and the factor causing it to blow is the movement of the sphere. In a similar way you will find that every cause of generation and corruption goes back, in the last resort, to the movement of the sphere. Now when, in the last resort, we have gone back to this sphere, which is in motion, it follows necessarily that it must have a mover, according to what has been set forth before in the seventeenth premise. Now the mover cannot but be either in the moved or outside it, for this is a necessary division. Now if the mover is outside the sphere, it cannot but be either a body or not a body; in which latter case it should not be said to be outside the sphere, but separate from it, for what is not a body is not said to be outside a body except through an extension of the meaning of the expression. If, however, its mover is in it — I mean the mover of the sphere — it cannot but be either that the mover is a force distributed in the whole of the body of the sphere and divisible through the latter’s being divided — as heat in fire — or that it is a force in the sphere that is not divisible — as are the soul and the intellect — just as has been expounded before the tenth premise. There is, accordingly, no doubt as to the mover of the sphere being one of these four: either another body outside it, or separate from it,4 or a force distributed in it, or an indivisible force.
Now the first supposition — namely, that the mover of the sphere is another body outside the sphere — is absurd, as I shall point out. For if it is a body, it must — as has been set forth in the ninth premise — be in motion when moving another body. Now in that case, this sixth body5 likewise must be in motion when moving another body. Accordingly it would necessarily follow that it is moved by a seventh body. This in its turn must be supposed to be in motion. Accordingly it would follow necessarily that an infinite number of bodies must exist and that only in that case is the sphere in motion. Now this is absurd, [6b] as has been set forth before in the second premise.
The third possibility — namely, that the mover of the sphere is a force distributed in the latter — is likewise absurd, as I shall point out. For the sphere is a body and in consequence necessarily finite, as has been set forth before in the first premise. In consequence its force must be finite, as has been set forth in the twelfth premise. Hence this force must be divisible if the sphere is divided, as has been set forth in the eleventh premise. Hence it cannot move something for an infinite time, as we have supposed that it does in the twenty-sixth premise.
As for the fourth possibility — namely, that the mover of the sphere is an indivisible force subsisting in the sphere, as for example man’s soul does in man — it is likewise absurd that this mover alone should be the cause for this perpetual motion, even if it is indivisible. The explanation of this lies in the fact that if this mover is the first mover of the sphere, it also must be in motion according to accident, as has been mentioned in the sixth premise.
I shall add here the explanation that follows. When, for example, the soul of a man, which is his form, moves him to go up from the house to an upper chamber, it is the body that is in motion according to essence, the soul being the first mover according to essence. However, the soul is in motion according to accident, for through the transporting of the body from the house to the upper chamber, the soul, which was in the house, was transported and came to be in the upper chamber. Now if the action of moving exerted by the soul would come to rest, that which was moved by it, namely, the body, also would come to rest. But then through the fact that the body would come to rest, the accidental motion, which had come to the soul, would be abolished. Now, everything that is moved according to accident must of necessity come to rest, as has been mentioned in the eighth premise. When, however, it comes to rest, that which is moved by it likewise comes to rest. It follows accordingly of necessity that the first mover in question [7a] necessarily must have another cause subsisting outside the whole, which is composed of a mover and of a moved. When this cause, which is the beginning of movement, is present, the first mover, which subsists in this whole, moves that in it which may be moved. When, however, it is not present, that which may be moved in the whole is at rest.6 For this reason the bodies of animals are not perpetually in motion, even though there is in every one of them an indivisible first mover. For their mover does not move them perpetually according to essence, for the factors that incite it to cause to move are matters outside it: either quest for what agrees with that particular animal, or flight from what disagrees with it, or again an imagination or a representation in the case of those animals that have representations.7 When acted upon by these factors, the mover causes movement. When doing this, it itself is moved accidentally. And accordingly there is no doubt about its coming to rest at a certain time, as we have mentioned. If, however, the mover of the sphere were in it in this manner, it would not be able to be in motion eternally.
Accordingly, if the motion in question is perpetual and eternal, as is stated by our adversary — and this is possible, as has been mentioned in the thirteenth premise — it follows necessarily, according to this opinion,8 that the first cause of the movement of the sphere conforms to the second possibility; I mean to say that it is separate from the sphere according to what is required by the above division.9 It accordingly has been demonstrated that it is necessary that the mover of the first sphere, if the movement of the latter is regarded as eternal and perpetual, should not at all be a body or a force in a body; in this way the mover of this sphere would have no movement, either according to essence or to accident, and would not be subject to division or to change, as has been mentioned in the seventh and the fifth of the premises. Now this is the deity, may His name be sublime; I am referring to the first cause moving the sphere. And it is absurd that there should be two or more of them because it is absurd that there should be multiplicity in the separate things, which are not bodies, except when [7b] one of them is a cause and the other an effect, as has been mentioned in the sixteenth premise. It has also been made clear that this first cause does not fall under time because it is impossible that there should be movement with regard to it, as has been mentioned in the fifteenth premise. Accordingly this speculation has led by means of a demonstration to the knowledge that it is impossible that the sphere should move itself in an eternal motion; that the first cause to which its being set in motion is due, is not a body or a force in a body; and that this first cause is one and unchangeable because its existence is not conjoined with time. These are the three problems with regard to which the most excellent among the philosophers gave demonstrations.
A second speculation made by them. Aristotle propounded, by way of introduction, a premise that runs as follows: Supposing that there exists a thing composed of two things and that one of these two things exists separately outside this compound thing, it follows necessarily that the other thing also must exist outside the compound thing.10 For if the existence of these two things had required that they exist only together, as do matter and natural form, one of them would not have existed in any way without the other. Accordingly, the fact that one of them exists separately is a proof for the absence of an obligatory mutual connection. Consequently the second thing, which enters into the compound thing, must necessarily exist separately. The following example for this may be adduced: if oxymel exists and honey likewise exists by itself, it follows necessarily that vinegar must exist by itself. After having explained this premise, he says: We find that many things are composed of a mover and a moved. He means to say thereby that these things move other things, and, when moving the latter, are themselves moved by other things. This is manifest with regard to all the things that have an intermediate status as far as causing to move is concerned. Now we find that there exists a thing that is moved and does not at all cause to move; this is the last of the moved things. It follows accordingly that there must exist a mover that is not moved at all; this is the first mover.11 And inasmuch as no [8a] motion is possible in it, it is not divisible and not a body, and it does not fall under time, as has become clear in the preceding demonstration.
A third philosophic speculation about this subject is taken over from Aristotle’s argumentation, even though he sets it forth with a view to another purpose. This is how the argument is ordered. There is no doubt that there are existent things. These are the existent things that are apprehended by the senses. Now there are only three possible alternatives,12 this being a necessary division: namely, either no existents are subject to generation and corruption, or all of them are subject to generation and corruption, or some of them are subject to generation and corruption whereas others are not. Now the first alternative is clearly absurd, for we perceive many existents that are subject to generation and corruption. The second alternative is likewise absurd, the explanation of this being as follows: if every existent falls under generation and corruption, then all the existents and every one of them have a possibility of undergoing corruption. Now it is indubitable, as you know, that what is possible with regard to a species must necessarily come about. Thus it follows necessarily that they, I mean all existents, will necessarily undergo corruption. Now if all of them have undergone corruption, it would be impossible that anything exists, for there would remain no one who would bring anything into existence. Hence it follows necessarily that there would be no existent thing at all. Now we perceive things that are existent. In fact we ourselves are existent. Hence it follows necessarily, according to this speculation that if there are, as we perceive, existents subject to generation and corruption, there must be a certain existent that is not subject to generation and corruption. Now in this existent that is not subject to generation and corruption, there is no possibility of corruption at all; rather, its existence is necessary, not possible. He also says that, with reference to this existent’s being necessary of existence, there are two possibilities: this may be either in respect to its own essence or in respect to the cause of this existent. In the latter case, [8b] its existence and nonexistence are possible in respect to its own essence, but necessary in respect to its cause. Thus its cause would be necessary of existence, as has been mentioned in the nineteenth premise. Now it has been demonstrated that, of necessity, there can be no doubt that there is an existent that is necessary of existence in respect to its own essence. For without it, there would be no existent at all, neither one that is subject to generation and corruption, nor one that is not subject to them — if there is a thing that exists in this manner, as Aristotle states; I mean to say a thing that is not subject to generation and corruption because of its being an effect caused by a cause that is necessary of existence. This is a demonstration concerning which there can be no doubt, no refutation, and no dispute, except on the part of one who is ignorant of the method of demonstration. After this we shall say that it follows necessarily that the existence of everything that is necessary of existence with respect to its own essence can have no cause, as has been set forth in the twentieth premise; and that in anything that is necessary of existence there cannot be a multiplicity of notions, as has been mentioned in the twenty-first premise. Hence it follows necessarily that, as has been set forth in the twenty-second premise, it is not a body or a force in a body. It thus has been demonstrated in this speculation that there is an existent that is necessary of existence and is so necessarily with respect to its own essence, and that this existent has no cause for its existence and has no composition in itself, and for this reason is neither a body nor a force in a body. It is he who is the deity, may His name be sublime. Similarly it can be easily demonstrated that it is impossible that necessity of existence in respect to essence should exist in two beings. For the species, necessity of existence, is a notion that would be superadded to the essence of each one of these two supposed beings. Accordingly, none of them would be necessary of existence in virtue only of itself, but it would be necessary of existence in virtue of the notion representing the species — necessity of existence — a species subsisting both in that particular being and in another one. Now it has been made clear in a number of ways that no duality at all, nor [9a] the existence of an equal or of a contrary, can be true with reference to the necessary of existence. The cause of all this is the latter’s absolute13 simplicity and absolute13 perfection — leaving no residue outside its essence that pertains to the species, the necessary of existence — as well as the nonexistence in any way of a primary or secondary cause14 for it. Accordingly, nothing at all can be associated with the necessary of existence.
The fourth speculation, likewise philosophic. It is well known that we constantly see things that are in potentia and pass into actuality. Now everything that passes from potentiality into actuality has something outside itself that causes it to pass, as has been mentioned in the eighteenth premise. It is also clear that this something, which in one particular case causes to pass from potentiality to actuality, had been a cause of this passage in potentia and then only became such a cause in actu. Now the reason for its having been in potentia might lie either in an obstacle subsisting in its own right or in a relation — which had been absent before — between it and the thing it is to cause to pass from potentiality to actuality. When this relation is realized, it actually causes the thing to pass from potentiality to actuality. Now these two explanations necessarily require something that causes to pass from potentiality to actuality or a factor that puts an end to a hindrance. And the same thing must necessarily be said of the second something that causes to pass from potentiality to actuality or of the second factor that puts an end to a hindrance. And this series of causes or factors cannot continue to infinity. There is no doubt that, in the last resort, one must come to something that causes the passage from potentiality to actuality, that is perpetually existent in one and the same state, and in which there is no potentiality at all. I mean to say that in it, in its essence, there is nothing in potentia. For if there were possibility15 in its essence, the thing in question would at some time become nonexistent, as has been mentioned in the twenty-third premise. It is further impossible that the thing in question should be endowed with matter; rather is it separate from matter, as has been mentioned in the twenty-fourth premise. Now the being that is separate from matter, in which there is no possibility whatever, but that exists in virtue of its essence, is the deity. And it has already been made clear that He is not a body and that He is one, as has been mentioned in the sixteenth premise.
All these are demonstrative methods of proving the existence of one deity, who is neither a body nor a force in a body, while believing at the same time in the eternity [9b] of the world.
There is also a demonstrative method of refuting the belief in the corporeality of [God] and of establishing [God’s] unity. For if there were two deities it would follow necessarily that they must have one separately conceivable thing in which they participate, this being the thing in virtue of which each one of them merits being called a deity. They also must necessarily have another separately conceivable thing in virtue of which their separation came about and they became two. Now in virtue of the fact that in each of them there must be a separately conceivable thing other than the one subsisting in the other deity, each one of them must be composed of two separately conceivable things. Accordingly, as has been explained in the nineteenth premise, none of them can be a first cause or necessary of existence in respect to its own essence, but each of them must have several causes. If, however, the separately conceivable thing causing the separation between them exists in only one of them, the one in which the two separately conceivable things16 exist, is not according to his essence, existent of necessity.
Another method with regard to the belief in unity. It has already been established as true by means of a demonstration that all that exists is like one individual whose parts are bound up with each other, and that the forces of the sphere pervade this lowly matter and fashion it. At the same time it is impossible — and this has already been established as true — that one deity should be exclusively concerned with one part of what exists, and the other deity17 with another part; for one part is bound up with the other. According to the division of possibilities, the only hypotheses that remain open are that one deity acts during a certain time and the other during another time, or that both of them always act together so that no act is perfect unless it has been carried out by both of them together. Now the supposition that one of them acts during a certain time and the other during another time is absurd from several points of view. For if it were possible that during the time [10a] in which one of them acts the other should act also, what could be the cause necessitating that one of them acts during that time whereas the other remains inactive? If, however, it were impossible for one of them to act during the time in which the other acts, there consequently must be another cause that necessitates that at a given time it is possible for one of them to act whereas for the other it is impossible. For there is no differentiation in time as a whole; and the substratum for the action18 is one, and its parts are bound up with one another, as we have made clear. Furthermore, according to this supposition, each one of them would fall under time inasmuch as his work would be tied up with time. Furthermore, each one of them, at the time of his action, would have to pass from potentiality to actuality, and, in consequence, each one of them would need something that would cause him to pass from potentiality to actuality. Furthermore, possibility would subsist in the essence of each of them. If, however, they were supposed always to make together everything that is in existence, so that one of them would not act without the other, that also would be absurd, as I shall set forth. For in the case of any complex composed of parts, which cannot cause a certain act to become perfect except through the co-operation of each one of its parts, none of these parts is an agent in respect to its own essence or the first cause of the act; that first cause is the coming-together of the parts of the complex. Now it has been demonstrated that it is a necessary conclusion that what is necessary of existence can have no cause. Moreover the coming-together of the parts of the complex represents a certain act, which requires another agent, namely, one who causes the parts of the complex to come together. Now if the agent who causes the parts of the complex to come together — without which the act cannot become perfect — is one, he is indubitably the deity. If, however, this agent who causes the parts of this complex to come together is another complex, the same conclusions follow necessarily with regard to this second complex as with regard to the first. Thus there can be no doubt about ultimately reaching One who is the cause of the existence of this existent, which is one,19 whatever the manner of this may have been: whether through creating it in time after it had been nonexistent, or because it proceeds necessarily from this One. [10b] It has thus become clear, also according to this method, that the fact that all that exists is one, indicates to us that He who caused it to exist is one.
Another method of refuting the belief in the corporeality [of God]. As has been mentioned in the twenty-second premise, every body is a compound. Now there can be no doubt that every compound requires an agent, which is the cause of the subsistence of its form in its matter. Now it is most clear that every body is divisible and has dimensions. Accordingly, it is indubitably something to which accidents must be attached. Hence a body cannot be one, both because of its divisibility and because of its being a compound — I mean to say, because of its being two as far as statement is concerned. For every body is a certain body only because of some separately conceivable thing subsisting in it that is superadded to the fact of its being a body. In consequence, every body is necessarily provided with two separately conceivable things. Now it has been demonstrated that in the necessary of existence there is no composition in any way at all.
After having first set forth these demonstrations, I shall start to give an epitome of that method which is emphatically ours, as we have promised.