Summa contra Gentiles2.40 Chapter XL. That matter is not the first cause of the distinction of things

Furthermore, it is evident from the foregoing that the distinction of things is not on account of a diversity of matter as its first cause. For nothing determinate can proceed from matter except by chance: because matter is in potentiality to many things, of which if only one were to result, it must needs be that this happens in the minority of cases, and such is that which happens by chance, especially if we remove the intention of an agent. Now it was proved that the distinction of things is not from chance. It follows therefore that it is not on account of a diversity of matter, as its first cause.

Again. Those things which result from the intention of an agent, are not on account of matter as their first cause. For an active cause precedes matter in acting: because matter does not become an actual cause except in so far as it is moved by an agent. Wherefore if an effect is consequent upon a disposition of matter and the intention of an agent, it does not result from matter as its first cause. For this reason we find that those things which are referable to matter as their first cause, are beside the intention of the agent; for instance monsters and other mischances of nature. But the form results from the intention of the agent. This is proved thus. The agent produces its like according to its form, and if sometimes this fails, it is from chance on account of a defect in the matter. Therefore forms do not result from a disposition of matter as their first cause; on the contrary, matters are disposed in such a way that such may be their forms. Now the specific distinction of things is according to their forms. Therefore the distinction of things is not on account of the diversity of matter as its first cause.

Moreover. The distinction of things cannot result from matter except in those which are made from pre-existing matter. Now many things are distinguished from one another which cannot be made from pre-existing matter: for instance, the celestial bodies, which have no contrary, as their movement shows. Therefore the diversity of matter cannot be the first cause of the distinction of things.

Again. Whatever things having a cause of their being are distinct from one another, have a cause of their distinction: because a thing is made a being according as it is made one, undivided in itself and distinct from others. Now if matter, by its diversity, is the cause of the distinction of things, we must suppose that matters are in themselves distinct. Moreover it is evident that every matter has being from something else, since it was proved above that everything, that is in any way whatsoever, is from God. Therefore something else is the cause of distinction in matters: and consequently the first cause of the distinction of things cannot be a diversity of matter.

Again. Since every intellect acts for the sake of good, it does not produce a better thing for the sake of an inferior thing: and it is the same with nature. Now all things proceed from God Who acts by His intellect, as stated above. Therefore inferior things proceed from God for the sake of better things, and not vice versa. But form is more noble than matter, since it is its perfection and act. Therefore He does not produce such and such forms for the sake of such and such matters, but rather He produced such and * Ch. XV. Ch. xxiv.

such matters that there might be such and such forms. Therefore the specific distinction in things, which is according to their form, is not on account of their matter: but on the contrary matters were created diverse, that they might be suitable for diverse forms.

Hereby is excluded the opinion of Anaxagoras, who postulated an infinite number of material principles, which at first were mixed together in one confused mass, but which an intellect subsequently separated, thus establishing a distinction among things: as well as the opinions of any who held the distinction of things to be the result of various material principles.