In the course of this history certain distinctive domains of Being have come into view and have served as the primary guides for subsequent problematics: the ego cogito of Descartes, the subject, the "I", reason, spirit, person. But these all remain uninterrogated as to their Being and its structure, in accordance with the thoroughgoing way in which the question of Being has been neglected. It is rather the case that the categorial content of the traditional ontology has been carried over to these entities with corresponding formalizations and purely negative restrictions, or else dialectic has been called in for the purpose of Interpreting the substantiality of the subject ontologically.
If the question of Being is to have its own history made transparent, then this hardened tradition must be loosened up, and the concealments which it has brought about1 must be dissolved. We understand this task as one in which by taking the question of Being as our clue, we are to destroy the traditional content of ancient ontology until we arrive at those primordial experiences in which we achieved our first ways of determining the nature of Being—the ways which have guided us ever since.
In thus demonstrating the origin of our basic ontological concepts by an investigation in which their 'birth certificate' is displayed, we have nothing to do with a vicious relativizing of ontological standpoints. But this destruction is just as far from having the negative sense of shaking off the ontological tradition. We must, on the contrary, stake out the positive possibilities of that tradition, and this always means keeping it within its limits; these in turn are given factically in the way the question is formulated at the time, and in the way the possible field for investigation is thus bounded off. On its negative side, this destruction does not relate itself towards the past; its criticism is aimed at 'today' and at the prevalent  way of treating the history of ontology, whether it is headed towards doxography, towards intellectual history, or towards a history of problems. But to bury the past in nullity [Nichtigkeit] is not the purpose of this destruction; its aim is positive; its negative function remains unexpressed and indirect.
The destruction of the history of ontology is essentially bound up with the way the question of Being is formulated, and it is possible only within such a formulation. In the framework of our treatise, which aims at working out that question in principle, we can carry out this destruction only with regard to stages of that history which are in principle decisive.
In line with the positive tendencies of this destruction, we must in the first instance raise the question whether and to what extent the Interpretation of Being and the phenomenon of time have been brought together thematically in the course of the history of ontology, and whether the problematic of Temporality required for this has ever been worked out in principle or ever could have been.
1 '... der durch sie gezeitigten Verdeckungen.' The verb 'zeitigen' will appear frequently in later chapters. See H. 304 and our note ad loc.