What-is was not generated from what-is-not, because what-is-not cannot give rise to anything in addition to itself. This is the first enunciation of the principle "out of nothing, nothing comes to be,"? which was implicit in earlier Greek thought even as far back as Hesiod and which afterwards, because of Parmenides, became a touchstone for subsequent Greek cosmogonies.These arguments show that coming to be from what-is-not is impossible, which is... relevant in the first stage of a cosmogony. The arguments say nothing of more familiar cases of coming to be, which can be described in terms of changes among already existing things.