Abstract
Few theses characterize more especifically the metaphysics of Aquinas than the thesis of the real distinction between being and essence, the thesis of being as the act of the essence, the thesis of the ontological contingency of the universe and the conception of the cause of the existence of things as subsistent being. The aim of the present work is to prove that these theses, as well as others derived from them, like the claim of the identity of essence and being in God and that of God’s simplicity, result from the previous absolutization of essence, that is, from Aquinas’ essencialist and ontologizing interpretation of the fact that existent individuals are not explicitly mentioned in definitions.