Among the works we dispose of for the reconstitution of the metaphysical thought of Thomas Aquinas (1225-1274), we find the Quaestiones disputatae De Potentia Dei, written between 1265 and 1266. To know the philosophical itinerary (iter) of the De Potentia is an indispensable task not only for the exegesis of that work, but, above all, for determining the originality of the metaphysical synthesis of its author. The metaphysical itinerary of Aquinas is guided around two complementary ways: the way of resolution (via resolutionis) and the way of composition (via compositionis). Each of them considers being qua being in the light of the intrinsic causes (secundum rationem) or extrinsic causes (secundum rem). Examination of the De Potentia´s arguments reveals that the term a quo of the way of resolution by the intrinsic causes (via resolutionis secundum rationem) is the rising of the aristotelian dýnamis to the condition of potentia essendi, while its term ad quem consists of the resolution of all acts and of all perfections of beings in the actuality and in the perfection of the act of being (actus essendi). In an ulterior perspective, the beings are raised to the condition of participants of the selfsubsisting being (ipsum esse subsistens), thus fulfilling the itinerary of the way of the resolution by extrinsic causes (via resolutionis secundum rem). It is the overcoming by way of the resolution in esse of the antitheses on which our metaphysical inheritance is born (participation and causality, transcendence and immanence, platonism and aristotelism) that constitutes the most original contribution of Thomas Aquinas to the cultural life of the West.