The account of what nature was before creation in Ovid's Metamorphoses is really quite similar to what is said in Genesis in the Bible. Basically, Ovid is saying that the universe existed already, but it was a completely formless and chaotic place. Everything was all jumbled up and "indigested." There was no sun, no moon, no Earth, nothing that could be distinguished from anything else. In other words, it was accurate to refer to it as chaos.
From this chaos, either God or nature started to create order out of the chaos. The undifferentiated mass was separated out into various elements and the process of creation had begun.