The Philosophy of Illumination

Suhrawardī's main philosophical work, completed in 1186, a few years before his execution in Aleppo. Written in Arabic in a deliberately compact style, it has two parts. The first examines logic and criticises the Peripatetic philosophers who followed Ibn Sīnā: Suhrawardī argues that essential definitions cannot be achieved, and that notions such as existence and unity are only mental concepts, not real things added to what exists. The second part builds a metaphysics of light. Reality is ordered by degrees of intensity of light, from the Light of Lights through a hierarchy of immaterial lights down to dark bodies. The self knows itself directly, as a light aware of itself, and this immediate self-awareness is the model for knowledge by presence, in which the knower grasps the known without a representation. The book also describes an intermediate world of images between the intellectual and the physical, and its final sections treat the fate of souls after death and visionary experience.

It founded the Illuminationist school, offers a serious alternative to Avicenna's metaphysics, and is the key to later Persian philosophy up to Mullā Ṣadrā.