XVII. That the World is by nature Eternal.
We have shown above that the gods will not destroy the world. It remains to show that its nature is indestructible.
Everything that is destroyed is either destroyed by itself or by something else. If the world is destroyed by itself, fire must needs burn itself and water dry itself. If by something else, it must be either by a body or by something incorporeal. By something incorporeal is impossible; for incorporeal things preserve bodies—nature, for instance, and soul—and nothing is destroyed by a cause whose nature is to preserve it. If it is destroyed by some body, it must be either by those which exist or by others.
If by those which exist: then either those moving in a straight line must be destroyed by those that revolve, or vice versa. But those that revolve have no destructive nature; else, why do we never see anything destroyed from that cause? Nor yet can those which are moving straight touch the others; else, why have they never been able to do so yet?
But neither can those moving straight be destroyed by one another: for the destruction of one is the creation of another; and that is not to be destroyed but to change.
But if the World is to be destroyed by other bodies than these it is impossible to say where such bodies are or whence they are to arise.
Again, everything destroyed is destroyed either in form or matter. (Form is the shape of a thing, matter the body.) Now if the form is destroyed and the matter remains, we see other things come into being. If matter is destroyed, how is it that the supply has not failed in all these years?
If when matter is destroyed other matter takes its place, the new matter must come either from something that is or from something that is not. If from that-which-is, as long as that-which-is always remains, matter always remains. But if that-which-is is destroyed, such a theory means that not the World only but everything in the universe is destroyed.
If again matter comes from that-which-is-not: in the first place, it is impossible for anything to come from that which is not; but suppose it to happen, and that matter did arise from that which is not; then, as long as there are things which are not, matter will exist. For I presume there can never be an end of things which are not.
If they say that matter <will become> formless: in the first place, why does this happen to the world as a whole when it does not happen to any part? Secondly, by this hypothesis they do not destroy the being of bodies, but only their beauty.