Iamblichus (245-325 A.D.), was a Syrian Neoplatonist philosopher of Arab origin. He determined the direction that would later be taken by Neoplatonic philosophy. He was also the biographer of the Greek mystic, philosopher and mathematician Pythagoras.
He initially studied under Anatolius of Laodicea, and later went on to study under Porphyry, a pupil of Plotinus, the founder of Neoplatonism. He disagreed with Porphyry over the practice of theurgy; Iamblichus responds to Porphyry's criticisms of theurgy in a book attributed to him, De Mysteriis Aegyptiorum (On the Egyptian Mysteries). Only a fraction of Iamblichus' books have survived.