Summa contra Gentiles1.20 Chapter XX. That God is not a body

From the foregoing we are also able to prove that God is not a body.

For since every body is a continuous substance, it is composite and has parts. Now God is not composite, as we have shown. Therefore He is not a body.

Further. Every quantitative substance is somehow in potentiality: for that which is continuous is potentially divisible to infinity; and number can be infinitely augmented. Now every body is a quantitative substance. Therefore every body is in potentiality. But God is not in potentiality, but is pure act, as shown above. Therefore God is not a body.

Again. If God were a body, He would needs be a physical body, for a mathematical body does not exist by itself, as the Philosopher proves, since dimensions are accidents. Now He is not a physical body; for He is immovable, as we have proved, and every physical body is movable. Therefore God is not a body.

Moreover. Every body is finite, which is proved in regard both to spherical and to rectilinear bodies in i Coeli et Mundi. Now we are able by our intellect and imagination to soar above any finite body. Wherefore, if God were a body, our intellect and imagination would be able to think of something greater than God: and thus God would not exceed our intellect: which is inadmissible. Therefore He is not a body.

Furthermore. Intellective knowledge is more certain than sensitive. Now among natural things we find some that are objects of sense: therefore there are also some that are objects of intellect. But the order of powers is according to the order of objects, in the same way as their distinction. Therefore above all sensible objects there is an intelligible object existing in natural things. But every body that exists among things is sensible. Therefore above all bodies it is possible to find something more excellent. Wherefore if God were a body, He would not be the first and supreme being.

Again. A living thing is more excellent than any body devoid of life. Now the life of a living body is more excellent than that body, since thereby it excels all other bodies. Therefore that which is excelled by nothing, is not a body. But such is God. Therefore He is not a body.

Moreover. We find the philosophers proving the same conclusion by arguments based on the eternity of movement, as follows. In all everlasting movement the first mover must needs not be moved, neither per se nor accidentally, as we have proved above. Now the body of the heavens is moved in a circle with an everlasting movement. Therefore its first mover is not moved, neither per se nor accidentally. Now no body causes local movement unless itself be moved, because moved and mover must be simultaneous; and thus the body that causes movement must be itself moved, in order to be simultaneous with the body that is moved. Moreover no power in a body causes movement except it be moved accidentally; since, when the body is moved, the power of that body is moved accidentally. Therefore the first mover of the heavens is neither a body nor a power residing in a body. Now that to which the movement of the heavens is ultimately reduced as to the first immovable mover, is God. Therefore God is not a body.

Again. No infinite power is a power residing in a magnitude. But the power of the first mover is an infinite power. Therefore it does not reside in a magnitude. And thus God, Who is the first mover, is neither a body nor a power residing in a body.

The first proposition is proved as follows. If a power 1 7 and 8 Phys. See above, ch. xiii. a Ch. xiii.

residing in a magnitude be infinite, this magnitude is either finite or infinite. But there is no infinite magnitude, as proved in 3 Phys. and 1 Coeli et Mundi. And it is not possible for a finite magnitude to have an infinite power. Therefore in no magnitude can there be an infinite power.

That there cannot be an infinite power in a finite magnitude is proved thus. A great power produces in less time an equal effect, which a lesser power produces in more time: of whatever kind this effect may be, whether it be one of alteration, of local movement, or of any other kind of movement. Now an infinite power surpasses every finite power. It follows therefore that it produces its effect more rapidly, by causing a more rapid movement than any finite power. Nor can this greater rapidity be one of time. Therefore it follows that the effect is produced in an indivisible point of time. And thus moving, being moved, and movement will be instantaneous: the contrary of which has been proved in 6 Phys.

That an infinite power of a finite magnitude cannot cause movement in time, is proved thus. Let A be an infinite power; and AB a part thereof. This part therefore will cause movement in more time. And yet there must be proportion between this time and the time in which the whole power causes movement, since both times are finite. Suppose then these two times to be in proportion as to 10, for it does not affect this argument whether we take this or any other ratio. Now if we increase the aforesaid finite power, we must decrease the time in proportion to the increase of the power, since a greater power causes movement in less time. If therefore we increase it tenfold, that power will cause movement in a time which will be one-tenth of the time occupied by the first part that we took of the infinite power, namely AB. And yet this power which is ten times the aforesaid power is a finite power, since it has a fixed proportion to a finite power. It follows therefore that a finite power and an infinite power cause movement in an equal time: which is impossible. There- 1 Ch. v. 2 Ch. v. seqq. 3 Ch. iii.

fore an infinite power of a finite magnitude cannot cause movement in any time.

That the power of the first mover is infinite is proved thus. No finite power can cause movement in an infinite time. Now the power of the first mover causes movement in an infinite time, since the first movement is eternal. Therefore the power of the first mover is infinite. The first proposition is proved thus. If any finite power of a body causes movement in infinite time, a part of that body having a part of that power, will cause movement during less time, since the greater power a thing has, for so much the longer time will it be able to continue a movement, and thus the aforesaid part will cause movement in finite time, and a greater part will be able to cause movement during more time. And thus always according as we increase the power of the mover, we increase the time in the same proportion. But if this increase be made a certain number of times we shall come to the quantity of the whole or even go beyond it. Therefore the increase also on the part of the time will reach the quantity of time wherein the whole causes movement. And yet the time wherein the whole causes movement was supposed to be infinite. Consequently a finite time will measure an infinite time: which is impossible.

However, there are several objections to this chain of reasoning. One of these is that it might be held that the body which moves the first thing moved is not divisible, as is the case of a heavenly body: whereas the argument given above supposes it to be divided.

To this we reply that a conditional clause may be true though its antecedent be impossible. 'And if there be anything to disprove such a conditional, the antecedent is impossible. Thus if anyone disprove this conditional, // a man flies, he has wings, the antecedent would be impossible. It is in this way that we are to understand the process of the aforesaid reasoning. For this conditional is true, If a heavenly body be divided, its part will have less power than the whole. But this conditional is disproved if we suppose that the first mover is a body, on account of the impossibilities that follow. Wherefore it is clear that this is impossible. We can reply in the same way if objection be made to the increase of finite powers. Because it is impossible in natural things to find powers according to any proportion that there is between one time and any other time. And yet the conditional required in the aforesaid argument is true.

The second objection is that, although a body be divided, it is possible for a power of a body not to Be divided when the body is divided, thus the rational soul is not divided when the body is divided.

To this we reply that by the above argument it is not proved that God is not united to the body as the rational soul is united to Che human body, but that He is not a power residing in a body, as a material power which is divided when the body is divided. Wherefore it is also said of the human intellect that it is neither a body nor a power in a body. That God is not united to the body as its soul, is another question.

The third objection is that if the power of every body is finite, as is proved in the above process; and if a finite power cannot make its effect to endure an infinite time; it will follow that no body can endure an infinite time: and consequently that a heavenly body will be necessarily corrupted. Some reply to this that a heavenly body in respect of its own power is defectible, but acquires everlastingness from another that has infinite power. Apparently Plato approves of this solution, for he represents God as speaking of the heavenly bodies as follows: By your nature ye are corruptible, but by My will incorruptible, because My will is greater than your necessity.

But the Commentator refutes this solution in Metaph. For it is impossible, according to him, that what in itself may possibly not be, should acquire everlastingness of being from another: since it would follow that the corruptible is changed into incorruptibility; and this, in his opinion, is impossible. Wherefore he replies after this fashion: that in a heavenly body whatever power there is, is finite, and yet it does not follow that it has all power; for, according to Aristotle (8 Metaph.) the potentiality to (be) somewhere is in a heavenly body, but not the potentiality to be. And thus it does not follow that it has a potentiality to not-be. It must be observed, however, that this reply of the Commentator is insufficient. Because, although it be granted that in a heavenly body there is no quasi-potentiality to be, which potentiality is that of matter, there is nevertheless in it a quasi-active potentiality, which is the power of being: since Aristotle says explicitly in i Cceli et Mundi, that the heaven has the power to be always. Hence it is better to reply that since power implies relation to act, we should judge of power according to the mode of the act. Now movement by its very nature has quantity and extension, wherefore its infinite duration requires that the moving power should be infinite. On the other hand being has no quantitative extension, especially in a thing whose being is invariable, such as the heaven. Hence it does not follow that the power of being a finite body is infinite though its duration be infinite: because it matters not whether that power make a thing to last for an instant or for an infinite time, since that invariable being is not affected by time except accidentally.

The fourth objection is that the statement that what causes movement in infinite time must have an infinite power, does not necessarily apply to those movers which are not altered by moving. Because such a movement consumes nothing of their power; wherefore they can cause movement for no less time after they have moved for a certain time, than before. Thus the power of the sun is finite, and, because its power is not diminished on account of its action, it can act on this lower world for an infinite time, according to nature.

To this we reply that a body moves not unless it be moved, as we have shown. Therefore, supposing a body not to be moved, it follows that it does not move. Now in anything that is moved there is potentiality to opposites, since the terms of movement are opposite to one another. Consequently, considered in itself, every body that is moved is possibly not moved. And that which is possibly not moved is not apt of itself to be moved for an everlasting time: and consequently neither is it apt to move for a perpetual time.

Accordingly the demonstration given above is based on the finite power of a finite body; which power cannot of itself move in an infinite time. But a body which of itself is possibly moved and not moved, and possibly moves and does not move, can acquire perpetual movement from some cause; and this cause must needs be incorporeal. Wherefore the first mover must needs be incorporeal. Hence according to nature nothing hinders a finite body, which acquires from another cause perpetuity in being moved, from having also perpetuity in moving: since also the first heavenly body, according to nature, can cause a perpetual circular movement in the lower bodies, according as one sphere moves another. Nor is it impossible, as the Commentator maintains, for that which is, of itself, in potentiality to being moved and not moved, to acquire perpetual movement from something else, as he supposed it impossible as regards perpetuity of being. For movement is a kind of outflow from the mover to the thing movable, and consequently a movable thing can acquire perpetual movement from something else, without having it by nature. On the other hand to be is something fixed and quiescent in a being, and consequently that which is, of itself, in potentiality to not-be, cannot, as he says, in the course of nature, acquire from something else perpetuity of being.

The fifth objection is that according to the above reasoning there does not appear to be more reason why there should not be an infinite power in a magnitude than outside a magnitude: for in either case it would follow that it moves in not-time.

To this it may be replied that finite and infinite are found in a magnitude, in time and in movement in a univocal sense, as proved in and 6 Phys., wherefore the infinite in one of them removes a finite proportion in the others: whereas in things devoid of magnitude there is neither finite nor infinite unless equivocally. Hence the above course of reasoning has no place in suchlike powers.

But another and better answer is that the heaven has two movers. One is its proximate mover, which is of finite power, and thence it is that its movement is of finite velocity. The other is its remote mover, which is of infinite power, whence it is that its movement can be of infinite duration. Thus it is clear that an infinite power which is not in a magnitude, can move a body not immediately in time: whereas a power which is in a magnitude must needs move immediately, since no body moves without itself being moved. Wherefore, if it moved, it would follow that it moves in not-time.

Better still it may be replied that a power which is not in a magnitude is an intellect, and moves by its will. Wherefore it moves according to the requirement of the movable and not according to the proportion of its strength. On the other hand a power that is in a magnitude cannot move save by natural necessity, for it has been proved that the intellect is not a bodily force. Wherefore it causes movement necessarily according to the proportion of its quantity. Hence it follows that if it moves anything it moves it instantaneously. In this sense then, the foregoing objections being refuted, proceeds the reasoning of Aristotle.

Moreover. No movement that proceeds from a bodily mover can be continuous and regular: because a bodily mover, in local movement, moves by attraction or repulsion, and that which is attracted or repelled is not disposed in the same way towards its mover from the beginning to the end of the movement, since at one time it is nearer to it and at another time further from it: and thus no body can cause a continuous and regular movement. On the other hand the first movement is continuous and regular, as is proved in 8 Phys. Therefore the mover of the first movement is not a body.

Again. No movement that tends towards an end which passes from potentiality to actuality, can be perpetual: since, when it arrives at actuality, the movement ceases. If therefore the first movement is perpetual, it must be towards an end which is always and in every way actual. Now such is neither a body nor a power residing in a body; because these are all movable either per se or accidentally. Therefore the end of the first movement is not a body nor a power residing in a body. Now the end of the first movement is the first mover, which moves as the object of desire: and that is God. Therefore God is neither a body nor a power residing in a body.

Now though, according to our faith, it is false that the movement of the heavens is everlasting, as we shall show further on; it is nevertheless true that that movement will not cease, either on account of lack of power in the mover, or on account of the substance of the movable being corrupted, since we do not find that the movement of the heavens slackens in the course of time. Wherefore the aforesaid proofs lose nothing of their efficacy.

The truth thus demonstrated is in accordance with divine authority. For it is said (Jo. iv. 24): God is a spirit, and they that adore Him, must adore Him in spirit and in truth; and again (1 Tim. i. 17): To the King of ages, immortal, invisible, the only God; and (Rom. i. 20): The invisible things of God... are clearly seen, being understood by the things that are made, for things that are clearly seen not by the eye but by the mind, are incorporeal.

Hereby is refuted the error of the early natural philosophers, who admitted none but material causes, such as fire, water and the like, and consequently asserted that the first principles of things were bodies, and called them gods.

Among these also there were some who held that the causes of movement were sympathy and antipathy: and these again are refuted by the above arguments. For since according to them sympathy and antipathy are in bodies, it would follow that the first principles of movement are forces residing in a body. They also asserted that God was composed of the four elements and sympathy: from which we gather that they held God to be a heavenly body. Among the ancients Anaxagoras alone came near to the truth, since he affirmed that all things are moved by an intellect.

By this truth, moreover, those heathens are refuted who maintained that the very elements of the world, and the forces residing in them, are gods; for instance the sun, moon, earth, water and so forth, being led astray by the errors of the philosophers mentioned above.

Again, the above arguments confound the extravagances of the unlettered Jews, of Tertullian, of the Vadiani or Anthropomorphite heretics, who depicted God with human features; and again of the Manichees who affirmed God to be an infinite substance composed of light and spread abroad throughout boundless space. The occasion of all these errors was that in their thoughts about divine things they had recourse to their imagination, which can reflect none but corporeal likenesses. Wherefore it behoves us to put the imagination aside when we meditate on things incorporeal.