This paper intends to present the main lines of Heidegger’s philosophical program, as it was first presented in the book “Being and Time” and has been consistently developed in the later steps of his philosophical career. The adopted approach consists in confronting the program with Metaphysics, intended as a discipline concerning being, his structure and modes, having its own theoretical body of theses and history. This is not just one more point of view, among others, but the main question of Heidegger’s thought, which has, since his early years, put him in the way to thought. And this in two regards: not only because underlying Metaphysics stands the great question of being, his meaning and ground, that human beings bring with them as a fundamental purpose of their existence and history, but also because, as a science, it presents a structure which has become problematic and, therefore, demands to be clarified and examined in his presuppositions and limits. The interpretation here proposed of Heidegger’s thought in its whole tends to be read as a repeated essay of proceeding to a new instauration of Metaphysics through a constant dialogue and discussion of its fundamental theses concerning being. The main contribution that Heidegger intends to bring to this topic concerns the proposal of a new way of understanding being: an existentialistic one instead of the naturalistic approach of Greek essentialism. In Heidegger’s approach, temporality, in its human mode of occurrence, acquires a peculiar relevance to a new conception of being as a process of coming to presence.
