Tianyi Zhang offers in this study an innovative philosophical reconstruction of Shihab al-Din al-Suhrawardi's (d. 1191) Illuminationism. Commonly portrayed as either a theosophist or an Avicennian in disguise, Suhrawardi appears here as an original and hardheaded philosopher who adopts mysticism as a tool for philosophical investigation. Zhang makes use of Plato's cave allegory to explain Suhrawardi's Illuminationist project. Focusing on three areas-the theory of presential knowledge, the ontological discussion of mental considerations, and Light Metaphysics-Zhang convincingly reveals the Nominalist and Existential nature of Illuminationism and thereby proposes a new way of understanding how Suhrawardi's central philosophical ideas cohere.