Shihab al-Din Yahya al-Suhrawardi trained as an orthodox Avicennan Peripatetic philosopher before turning against the school that had formed him. His objection was methodological as much as doctrinal: definitions built from genus and differentia, he argued, can never actually capture the reality of a simple thing, because a definition is composed of parts and the simplest realities have none. In their place he proposed knowledge by presence, an immediate self-awareness that light has of itself, and built a cosmology graded by intensities of light and darkness rather than by the Peripatetic ladder of substance and accident.
He wrote in both Arabic and Persian, and drew deliberately on pre-Islamic Persian wisdom literature and Hermetic material alongside the Neoplatonic inheritance every falsafa thinker shared, presenting himself as reviving an ancient wisdom rather than founding something new. The Safavid philosopher Mulla Sadra took Illuminationist metaphysics as a serious rival to Peripatetic philosophy and answered it in his own transcendent philosophy, one reason later tradition remembers Suhrawardi as the founder of a distinct Ishraqi school with its own lineage of commentators.
Recent scholarship is more cautious. Suhrawardi's harshest modern readers treat Hikmat al-Ishraq as an internal critique of Avicenna rather than a wholesale departure from Peripatetic philosophy, and question whether a coherent, continuously transmitted Illuminationist school existed before later interpreters, Corbin prominent among them in the twentieth century, made it one. Executed at about thirty-six on charges that mixed philosophy with heresy, Suhrawardi left too small and too difficult a corpus to settle the question himself.