"In the First Part of his poem... Parmenides [is] chiefly interested to prove... it is; but it is not... obvious... what it is... that is. He says simply, What is, is. ...[W]e are accustomed to ...distinctions between ...kinds and degrees of reality, and we do not see which ...is meant. Such distinctions... were... unknown in those days. "That which is," with Parmenides, is primarily... matter or body; only it is not matter ...distinguished from anything else. It is... spatially extended; for it is... spoken of as a (fr. 8, 40). ...Aristotle tells us ...Parmenides believed in none but a sensible reality, which ...includes any ...perceived if the senses were more perfect ..."