The distinction between existence and essence in contingent beings is one of the foundational doctrines of medieval philosophy. Building upon Neoplatonic precursors, thinkers such as Avicenna and Aquinas debated its nature. However, one Islamic philosopher, who had an enormous influence on the development of philosophical discourse in Iran, subverted the traditional Peripatetic vision of reality and disputed the ontological nature of existence. Through a critique of the Peripatetic notion of existence, Suhrawardi demonstrated the irrelevance of the distinction for metaphysical inquiry, (...) which should, instead, rely upon an eidetic vision of the 'hierarchy of lights'. I shall explain why the later tradition advocated an essentialist reading of Suhrawardi and suggest that the Platonic hermeneutic of essential vision which Suhrawardi expounds, might be the reason for it. Later philosophers in the Islamic tradition had mistaken methodology for a description of reality. (shrink)