This is the last part proving God is not a body (more proofs, that is; we have already had several), a proposition which in unfamiliar to moderns and therefore not under much dispute, except for the steady stream of demiurges put forth by modern atheists as misconceptions of who or what God is. Yet I see that we’re growing weary of this subtopic, and so we’ll finish it today, and in a circumscribed fashion. I’ll also keep my footnotes to a minimum. Don’t forget we already know the Unmoved Mover, God, is outside time, i.e. is eternal. There are a lot of infinities involving God, and today we meet some of them. Next week, we start on a new and essential topic, that God is His own essence.
Chapter 20: That God is not a body
…13That 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.i
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…ii
16The 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.iii
17To 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 the 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.
18The 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.iv
19But the Commentator refutes this solution in 11 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.v 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 1 Coeli 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…
28Again. 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…vi
31Hereby 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.
32By 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.vii
i[Comment updated to fix stupid typo.] Don’t forget to review what these terms mean. The first movement is not some movement that caused the universe to start on its way in the dim dark past. It is the movement that starts all other movements, and we have seen that it must take no time. Again, I ask you to review Chapter 13. And Chapter 17, which proves God is not made of matter, and Chapter 15, which proves God is eternal. These are all premises here.
iiThis is not as bad as it looks when you first scan it. Read it. Two objections answered about conditionals and divided bodies are skipped.
iiiThe first time we hear the soul is immaterial! See also the next point, at that word “united.” This is only a hint of what is to come in other books of STG. Book One is all God all the time. Do not become a Descartesian over this one small word.
iv“For the sword outwears its sheath…And the soul wears out the breast.”
vSo much for slavishly following his predecessor!
viThis is pretty, but you must have Chapter 13 assimilated before you understand what he’s talking about. For instance, movement is actualization of a potential, and some actual power must actualize the potential. Potentials are powerless. (There’s a new business slogan for you.)
viiThe two-paragraph passage has interest in itself, as philosophical history, but is also proof that progress can be and is had in philosophy and theology, just like in science. Decay and distraction, again just in like science, also happen. Theology is thus, in the same sense as science, self correcting. Cf. Bk. II., ch. lvi.
 Cf. Ch. xxvii.
 Timaeus xli.
 D. 7, iv. 6.
 Ch. iii. 4; xii. 3.
 See above: But the Commentator…p. 46.
 3, iv. 11; 6, ii. 8.
 AverroÃ«s, 12 Metaph. t. c. 41.
 See above: To this we reply…p. 46.
 Ch. vii. seqq.
 Cf. ch. xiii.: Since, however,…p. 31.
 Bk. IV., ch. xcvii.
 Cf. 1 Phys. ii.