Chapter 27: That God Is Not In The Form Of A Body
1 ACCORDINGLY, having shown that God is not the being of all,i it can be proved in like manner that God is not the form of any thing.
2 For the divine being cannot be the being of a quiddity that is not it own being, as shown above. Now that which is the divine being itself is no other than God. Therefore it is impossible for God to be the form of any other thing.ii
3 Further. The form of a body is not its very being but the principle of its being. But God is being itself. Therefore God is not the form of a body.
4 Again. The union of form and matter results in a composite, and this is a whole in respect of form and matter. Now the parts are in potentiality with respect to the whole: but in God there is no potentiality. Therefore it is impossible for God to be the form united to any thing.
5 Again. That which has being per se, is more excellent than what has being in another. Now every form of a body has being in another. Since then God is the most excellent being, as the first cause of being, He cannot be the form of any thing.iii
6 Moreover, this can also be proved from the eternity of movement, as follows. If God were the form of a movable thing, since He is the first mover, the composite will be its own mover. But that which moves itself can be moved and not moved. Therefore it is in it to be either. Now a thing of this kind has not of itself indefectibility of movement. Therefore above that which moves itself we must place something else as first mover, which confers on it perpetuity of movement. And thus God Who is the first mover is not the form of a body that moves itself.iv
7 This argument avails for those who hold the eternity of movement. Yet if this be not granted the same conclusion may be drawn from the regularity of the heavenly movement. For just as that which moves itself can both be at rest and be moved, so can it be moved with greater or less velocity. Wherefore the necessity of uniformity in the heavenly movement depends on some higher principle that is altogether immovable, and that is not the part, through being the form, of a body which moves itself.v
8 The authority of Scripture is in agreement with this truth. For it is written in the psalm: Thy magnificence is elevated above the heavens; and (Job xi. 8, 9): He is higher than heaven, and what wilt thou do?…the measure of Him is longer than the earth, and deeper than the sea.…vi
iGod is not the universe. Pantheism is out.
iiAs proved before, God’s existence and essence are the same; existence itself is not a body; a body is partly in act, partly in potential, but in God there is no potential; just as God is not made of material stuff; thus God is not a body. These same (now proven) premises are picked up in arguments 3 and 4.
iiiThe thing to recall here is that objects, like bodies, are composites of form and matter. The same matter under the “influence” of other forms is a different object; i.e. objects are instantiated forms. Ed Feser’s favorite example (now forever stuck in my head) is rubber balls and erasers: two objects made of the same matter, but with different forms. But God is not made of matter, and God’s form is His existence, therefore He is not a body.
ivWe ever come back to Chapter 13, which is best to review. So much flows from the demonstration that God is Unmoved Mover, the Uncaused Cause, and other nicknames, that it is astonishing. The proof here flows directly (and easily).
vIt’s as well here as anywhere to remind us of the kind of movement Aquinas spoke of in his proof of God being the First Cause. He was not talking about the kind of movement like dominoes, where one pushes another and so on. He meant the here-and-now bottom-down ultimate cause of all movement. If you can’t remember this distinction, do the review before commenting.
viI normally leave the scriptural arguments out because they are not convincing to modern audiences. However in this case, since the question has often arise that since Jesus was in the form of a body, and in the Eucharistic species, and that Jesus is part of the Trinity, i.e. is God, does it not follow that God is a body? It does not. Jesus is God, and had a fully divine nature. But he was also a man and had a human nature, a nature that required a body. That part of him was not divine; it was human flesh, just like ours. The Eucharistic is likewise of two natures, divine and mundane. The bread is there, but do is the divine. Now how are these miracles brought about? I haven’t the slightest idea.
Likewise, when scripture uses figurative or metaphorical language (“Seated a the right hand of God…”), it is just that: figurative or metaphorical. Avoid the atheist temptation to read all of the Bible literally.
 Ch. xxii.
 Ch. xvi.
 Ch. xiii.
 Cf. chs. xiii., xx.
 Ps. viii. 2.
 Vulg., broader.
 Sum. Th. P. I., Q. iii., A. 8.