Öz In this article, I attempt at exploring Parmenides’ understanding of Being, that is, the notion of esti, and the basic function of esti in his overall monistic vision. I also discuss, in this context, the identity of einai and noein, the internal connections between esti and aletheia as well as what he means by the concept of logos. I argue in detail that Parmenides’ monism has a very peculiar character in that he does not speak about one big single entity, but about the uniqueness of Being itself as the ground of all things in the cosmos. In that sense, one can qualify it as non-material monism and, at the same time, as non-ontical monism. But it also contains an identity philosophy, that is, the view that Being can only be spoken of in terms of identity statements. I try to develop the thesis that it is possible to interpret Parmenides’ reflections on esti with respect to the difference between Being itself and a being, (the ontological difference) which, arguably, corresponds to the way Parmenides contrasts esti vis-à-vis plurality and change, while identifying the former with pure being (to eon) and the latter with non-being (to me eon).