Book Zeta of Aristotle's metaphysics

Aristotle is probably the most important thinker of Western civilization, and his Metaphysics —for sure— is his most important work , and the 'ousia trilogy' (boks Zeta, Ēta and Theta) is widely accapted as the core of Metaphysics. The first book of the ousia trilogy, namely Zeta, is known as a problematic introductory lecture on ousia that is inconsistent with Aristotle's simple summary on the case in his Categories. This humble work of master's thesis, in which the clarification of the analyses on ousia in Zeta is aimed, demonstrates the compatibility of Aristotle's notion of ousia in Zeta with the one in Categories. That is, as he does in Categories, Aristotle in Zeta claims that the primary (prôtê) ousia are the particulars (kath' hekasta) which exist separately (khôriston) and actually (entelekheia) as a concrete whole (synolon) of matter (hyle) and form (eidos), in other words as a this (tode ti), and that the universals —especially species (eidos) and genus (genos)— may be accepted as ousia only in a secondary sense. Keywords: Aristotle, Metaphysics, Categories, ousia, substance, essence, particulars, separate, actuality, form, matter, concrete whole, this, universals, species, genus.