Everything that is destroyed is either destroyed by itself or by something else. If the world is destroyed by itself, fire must needs burn of 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. … 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.

XVII. That the World is by nature Eternal. - On the Gods and the Cosmos