kalām theologian Fakhr al Dīn al-Rāzī (d. 1209) and the last great philosopher in the post-Hellenic tradition, Naṣīr al-Dīn al Ṭūsī (d. 1274). In particular, Shaykh Aḥmad worked two centuries after Mullā Sadrā (d. 1640–41). Tha latter was both a mystic and a systematic rationalist whose influence is to be felt in Eastern Islam up to this day. The work of Mullā Sadrā, through e.g., his theory of motion in the category of substance, marked the beginning of a turn towards process philosophy in Muslim scholasticism, a turn marked by a still strict adherence to the Peripatetic method. My general contention is that Shaykh Aḥmad, whose philosophy in part consists of a critique of Mullā Sadrā, went beyond the confines of Muslim scholasticism and Peripatetic technique to develop a true process metaphysics and cosmology, in contrast to the more traditional substance metaphysics. In the article I argue that Shaykh Aḥmad's approach to the famous distinction between essence and existence is an exemplification of a true process metaphysics and cosmology.¹" /> The polarity of existence and essence according to shaykh Ahmad al-Ahsa'i - Samawi Hamid Idris | sdvig press