A relatively simple argument today. God is not made of stuff. Who would disagree? Pagans, perhaps. For example, the god of the atheists is a demiurge, a sort of superior created or “evolved” being, and therefore made of matter. But not God. What’s nifty about today’s discussion is the role of “chance”. For that, we turn back (again) to Aristotle.
Chapter 17: That in God there is no matter
1 FROM this it follows that God is not matter.i
2 For matter, such as it is, is in potentiality.ii
3 Again. Matter is not a principle of activity: wherefore, as the Philosopher puts it, efficient and material causes do not coincide. Now, as stated above, it belongs to God to be the first efficient cause of things. Therefore He is not matter.iii
4 Moreover. For those who referred all things to matter as their first cause, it followed that natural things exist by chance: and against these it is argued in 2 Phys. Therefore if God, Who is the first cause, is the material cause of things, it follows that all things exist by chance.iv
5 Further. Matter does not become the cause of an actual thing, except by being altered and changed. Therefore if God is immovable, as proved above, He can nowise be a cause of things as their matter.v
6 The Catholic faith professes this truth, asserting that God created all things not out of His substance, but out of nothing.vi
7 The ravings of David of Dinant are hereby confounded,vii who dared to assert that God is the same as primary matter, because if they were not the same, they would needs differ by certain differences, and thus they would not be simple: since in that which differs from another thing by a difference, the very difference argues composition.
Now this proceeded from his ignorance of the distinction between difference and diversity. For as laid down in 10 Metaph. a thing is said to be different in relation to something, because whatever is different, differs by something, whereas things are said to be diverse absolutely from the fact that they are not the same thing.
Accordingly we must seek for a difference in things which have something in common, for we have to point to something in them whereby they differ: thus two species have a common genus, wherefore they must needs be distinguished by differences. But in those things which have nothing in common, we have not to seek in what they differ, for they are diverse by themselves. For thus are opposite differences distinguished from one another, because they do not participate in a genus as a part of their essence: and consequently we must not ask in what they differ, for they are diversified by their very selves. Thus too, God and primary matter are distinguished, since, the one being pure act and the other pure potentiality, they have nothing in common.
iFrom last time, of course.
iiMatter can change, thus it is in potentiality, and we have seen from last time that God is not in potentiality.
iiiThis doesn’t appear controversial, but we have scarcely outlined the nature of cause. There are four kinds of cause: the formal (the form of the thing), material (what the thing is made of), efficient (what brings about the change), and final (the end or direction of the change). The material of the statue, say, is not its efficient cause. Much more on this later.
ivWe are now at Yours Truly’s favorite material. Aristotle (from 2 Phys iv):
Some people even question whether [chance and spontaneity] are real or not. They say that nothing happens by chance, but that everything which we ascribe to chance or spontaneity has some definite cause, e.g. coming ‘by chance’ into the market and finding there a man whom one wanted but did not expect to meet is due to one’s wish to go and buy in the market.
Similarly in other cases of chance it is always possible, they maintain, to find something which is the cause; but not chance, for if chance were real, it would seem strange indeed, and the question might be raised, why on earth none of the wise men of old in speaking of the causes of generation and decay took account of chance; whence it would seem that they too did not believe that anything is by chance…
There are some too who ascribe this heavenly sphere and all the worlds to spontaneity. They say that the vortex arose spontaneously, i.e. the motion that separated and arranged in its present order all that exists. This statement might well cause surprise.
For they are asserting that chance is not responsible for the existence or generation of animals and plants, nature or mind or something of the kind being the cause of them (for it is not any chance thing that comes from a given seed but an olive from one kind and a man from another); and yet at the same time they assert that the heavenly sphere and the divinest of visible things arose spontaneously, having no such cause as is assigned to animals and plants.
Yet if this is so, it is a fact which deserves to be dwelt upon, and something might well have been said about it. For besides the other absurdities of the statement, it is the more absurd that people should make it when they see nothing coming to be spontaneously in the heavens, but much happening by chance among the things which as they say are not due to chance; whereas we should have expected exactly the opposite.
Others there are who, indeed, believe that chance is a cause, but that it is inscrutable to human intelligence, as being a divine thing and full of mystery.
Aristotle says things which are for the sake of something can be caused by chance, and he gives this example (2 Phys v):
A man is engaged in collecting subscriptions for a feast. He would have gone to such and such a place for the purpose of getting the money, if he had known. [But he] actually went there for another purpose and it was only incidentally that he got his money by going there; and this was not due to the fact that he went there as a rule or necessarily, nor is the end effected (getting the money) a cause present in himself — it belongs to the class of things that are intentional and the result of intelligent deliberation. It is when these conditions are satisfied that the man is said to have gone ‘by chance’. If he had gone of deliberate purpose and for the sake of this — if he always or normally went there when he was collecting payments — he would not be said to have gone ‘by chance’.
Notice that chance here is not an ontological (material) thing or force, but a description or a statement of our understanding (of a cause). Aristotle concludes, “It is clear then that chance is an incidental cause in the sphere of those actions for the sake of something which involve purpose. Intelligent reflection, then, and chance are in the same sphere, for purpose implies intelligent reflection.”
And “Things do, in a way, occur by chance, for they occur incidentally and chance is an incidental cause. But strictly it is not the cause — without qualification — of anything; for instance, a housebuilder is the cause of a house; incidentally, a fluteplayer may be so.”
Chance used this way is like the way we use coincidence. But there is also spontaneity, which is similar: “The stone that struck the man did not fall for the purpose of striking him; therefore it fell spontaneously, because it might have fallen by the action of an agent and for the purpose of striking.”
Lastly, “Now since nothing which is incidental is prior to what is per se, it is clear that no incidental cause can be prior to a cause per se. Spontaneity and chance, therefore, are posterior to intelligence and nature. Hence, however true it may be that the heavens are due to spontaneity, it will still be true that intelligence and nature will be prior causes of this All and of many things in it besides.”
vIn short, since God is not movable, he can’t be made of matter, which is always movable.
viSuch a misunderstood word, nothing! It means just what it says. No thing. No fields, no forces, no fields, no equations, no quantum thises or thats, the absence of all entities. Now just you imagine what kind of Being could create something about of this real nothing. Only one: Being itself, I Am That I Am; which is to say, God.
viiZing! More proof that even saints can be contemptuous when the need arises. Notice very carefully that St Thomas does not ask for dialogue with David of Dinant, but is satisfied to destroy his argument.
 2 Phys. vii. 3.
 Ch. xiii.
 Chs. viii., ix.
 Ch. xiii.
 D. 9, iii. 6.
 Sum. Th. P. I., Q. iii., A. 8, ad 3.