I am composed of the formal and the material; and neither of them will perish into non-existence, as neither of them came into existence out of non-existence. Every part of me then will be reduced by change into some part of the universe, and that again will change into another part of the universe, and so on for ever. And by consequence of such a change I too exist, and those who begot me, and so on for ever in the other direction. For nothing hinders us from saying so, even if the universe is administered according to definite periods of revolution.