Book 9
11.99
But if both be alike causes, there will be nothing to be acted upon Nor can an incorporeal thing be the cause of an incorporeal thing, for the same reason. And a thing incorporeal cannot be the cause of a body, since nothing incorporeal creates anything corporeal. And, lastly, a body cannot be the cause of anything incorporeal, because what is produced must be of the material operated upon; but if it is not operated upon because it is incorporeal, it cannot be produced by anything whatever. Therefore there is no such thing as a cause. A corollary to this is their statement that the first principles of the universe have no real existence; for in that case something must have been there to create and act.
11.99
Furthermore there is no motion; for that which moves moves either in the place where it is or in a place where it is not. But it cannot move in the place where it is, still less in any place where it is not. Therefore there is no such thing as motion.
11.100
They used also to deny the possibility of learning. If anything is taught, they say, either the existent is taught through its existence or the non-existent through its non-existence. But the existent is not taught through its existence, for the nature of existing things is apparent to and recognized by all; nor is the non-existent taught through the nonexistent, for with the non-existent nothing is ever done, so that it cannot be taught to anyone.
