This book shows that Heidegger's "destruction" of the history of ontology with regard to Descartes' "cogito sum" does not mean "elimination" or annihilation, rather it is to be understood as "retrieval" and "reinterpretation" of the question Being; in this sense, Heidegger's critique of Descartes, his destruction of the history of ontology, and his existential analytic of the Being of Dasein contribute to the clarification of the meaning of Being. Therefore, we intend to explore and to interpret Heidegger's radical critique and to examine the destruction of the history of ontology with respect to his critique of Descartes' "cogito sum" and in his understanding of Dasein with respect to his interpretation of Temporality as Dasein's Being. Furthermore, this study will try to show how Heidegger's radical denial and critique of the history of ontology appears to be incomplete, and only partially justified with regard to all considerations of the meaning of Being, because they are partly true and partly insufficient in terms of our understanding of the question of the meaning of Being in the entire history of ontology.