Kitap 9
3
The same principle holds in all other cases too, so that the formula and knowledge of the actual must precede the knowledge of the potential.
3
In time it is prior in this sense: the actual is prior to the potential with which it is formally identical, but not to that with which it is identical numerically.
4
What I mean is this: that the matter and the seed and the thing which is capable of seeing, which are potentially a man and corn and seeing, but are not yet so actually, are prior in time to the individual man and corn and seeing subject which already exist in actuality.
5
But prior in time to these potential entities are other actual entities from which the former are generated; for the actually existent is always generated from the potentially existent by something which is actually existent—e.g., man by man, cultured by cultured—there is always some prime mover; and that which initiates motion exists already in actuality.
5
We have saidAristot. Met. 7.7, 8. in our discussion of substance that everything which is generated is generated from something and by something; and by something formally identical with itself.
6
Hence it seems impossible that a man can be a builder if he has never built, or a harpist if he has never played a harp; because he who learns to play the harp learns by playing it, and similarly in all other cases.
7
This was the origin of the sophists’ quibble that a man who does not know a given science will be doing that which is the object of that science, because the learner does not know the science. But since something of that which is being generated is already generated, and something of that which is being moved as a whole is already moved (this is demonstrated in our discussion on MotionAristot. Physics, 6.6.), presumably the learner too must possess something of the science.
8
At any rate from this argument it is clear that actuality is prior to potentiality in this sense too, i.e. in respect of generation and time.
