Abstract

The article examines the metaphysical doctrine of being of the great Iranian philosopher and theologian Sadr ad-Din Shirazi, who fundamentally renewed philosophy in Islamic world. The following aspects of this doctrine are considered: primacy and hierarchy of being; the distinction between the concept of being and the reality of being; the difference between being and entity; the difference between being and quiddity. The article shows the similarity of Sadr ad-Din Shirazi’s doctrine and certain Thomas Aquinas’s conceptions, especially his doctrine of the act of being. Both philosophers elaborated the ontological difference between being and entity. Therefore, they can not be included in the “oblivion of being” tradition which is the main feature of the history of European metaphysics, according to Martin Heidegger.