of another incorporeal thing for the same reason. Also, an incorporeal thing cannot be the cause of a body, because nothing that is incorporeal can produce a body. Nor, on the other hand, can a body be the cause of anything incorporeal, because in every production there must be some passive subject matter; but, as what is incorporeal is by its own nature protected from being a passive subject, it cannot be the object of any productive power. There is, therefore, no such thing as any cause at all. From all which it follows, that the first principles of all things have no reality; for such a principle, if it did exist, must be both the agent and the efficient cause.
Again, there is no such thing as motion. For whatever is moved, is moved either in the place in which it is, or in that in which it is not. It certainly is not moved in the place in which it is, and it is impossible that it should be moved in the place in which it is not; therefore, there is no such thing as motion at all.
They also denied the existence of all learning. If, said they, anything is taught, then either that which does exist is taught in its existence or that which does not exist is taught in its non-existence; but that which does exist is not taught in its existence (for the nature of all existent things is visible to all men, and is known by all men); nor is that which does not exist taught in its non-existence, for nothing can happen to that which does not exist, so that to be taught cannot happen to it.
Nor again, say they, is there any such thing as production. For that which is, is not produced, for it exists already; nor that which is not, for that does not exist at all. And that which has no being nor existence