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.

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