Francis J. Beckwith, St. Thomas Aquinas and the Inadequacy of Intelligent Design

"Ethan" comments and cites St. Thomas:

Accordingly, there is diversity and inequality in things created, not by chance, not as a result of a diversity of matter, not on account of certain causes or merits intervening, but from God’s own intention…

The distinction of things is not from chance… those things which are distinct by their forms are not distinct by chance, but perhaps those things are, whose distinction is from matter. But the distinction of species is from the form, and the distinction of singulars in the same species, is from matter. Wherefore the specific distinction of things cannot be from chance…

It follows therefore that theform of the universe is intended and willed by God. Therefore it is not from chance: for we ascribe to chance those things which are beside the intention of the agent. Now the form of the universe consists in the distinction and order of its parts. Therefore the distinction of things is not from chance.

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 opinions of any who held the distinction of things to be the result of various material principles.

I'll have to look this up when I get a chance.