Book 9
11.98
Therefore a cause can only be an object of thought; inasmuch as, if it be a cause, it must bring with it that of which it is said to be the cause, otherwise it will not be a cause. Just as a father, in the absence of that in relation to which he is called father, will not be a father, so too with a cause. But that in relation to which the cause is thought of, namely the effect, is not present; for there is no coming into being or passing away or any other process: therefore there is no such thing as cause. Furthermore, if there is a cause, either bodies are the cause of bodies, or things incorporeal of things incorporeal; but neither is the case; therefore there is no such thing as cause. Body in fact could not be the cause of body, inasmuch as both have the same nature. And if either is called a cause in so far as it is a body, the other, being a body, will become a cause.
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.
