Book 12
5
Nor is it satisfactory to say that all things were together, for they differ in their matter, since otherwise why did they become an infinity and not one? For Mind is one; so that if matter is also one, only that could have come to be in actuality whose matter existed potentially. The causes and principles, then, are three; two being the pair of contraries, of which one is the formula or form and the other the privation, and the third being the matter.This classification is found in Aristot. Physics 1.6, 7, but is foreign to the main treatise of the Metaphysics. See Introduction.
1
We must next observeSee Introduction. that neither matter nor form (I mean in the proximate sense) is generated. All change is of some subject by some agent into some object. The agent is the immediate mover; the subject is the matter; and the object is the form. Thus the process will go on to infinity if not only the bronze comes to be round, but also roundness or bronze comes to be; there must, then, be some stopping-point.
2
We must next observe that every substance is generated from something which has the same name (substances including not only natural but all other products). Things are generated either by art or by nature or by chance or spontaneously. Art is a generative principle in something else; nature is a generative principle in the subject itselfIn natural reproduction the generative principle is obviously in the parent. But the offspring is in a sense a part of the parent, and so Aristotle identifies the two.(for man begets man); the other causes are privations of these.Cf. Aristot. Met. 11.8.12 n.
