What is what-is?

"This book interprets the poem by the pre-Socratic philosopher, Parmenides, in a way that differs fundamentally from traditional interpretations. While some recent studies show that the poem uses the word "is" as a copula rather than a substantive, a close analysis of the Greek text shows that Parmenides did not deny the reality of a plurality of sense perceivable objects, but argued that each is an individual homogeneous unity that emerged from a mixture of opposite elements."--Jacket.