Natural reason and the ontologization of the metaphysics in Aquinas

The aim of the article is to analyze and to affirm two theses. First, to show that, for Aquinas, the existence of God is not the condition for the metaphysics as a science and, second, that the Thomistic metaphysics leads to the notion of being (ens) which is the fundament of all acts of knowledge. To show that we analyze Aquinas?s theory of knowledge. That entails the discussion on the order in the knowledge, the short analysis of the rational soul and the role of the judgment in Aquinas?s metaphysics. Finally, we investigate the technical and the methodological tool which Aquinas calls via resolutionis and its role in the understanding of Aquinas?s notion of ens as a fundament of any knowledge.