Our purpose is to show the philosophical reasons that led Martin Heidegger to introduce Suárez’s metaphysics in the formation of his existential ontology. We will take as a guiding principle the history of “Being” and more specifically of its being forgotten in favor of “being”, which Heidegger developed in several writings of him as a negative moment, but at the same time fundamental and previous to the presentation of his conception of metaphysics. In this account we will point out to the crucial role that was played, in the Heideggerian project of reinterpreting metaphysics, by the idea of Greek metaphysics and in particular of Aristotelian metaphysics. We shall address this issue at some length because we hold that the concept of Suárez...