Porphyry
Phoenician Neoplatonic philosopher (c. 234–c. 305), born in Tyre (in present-day Lebanon) under the Syriac name Malchus, initially trained under Longinus in Athens before moving to Rome to study with Plotinus, whose closest and most intellectually brilliant disciple he became, going through a profound existential and depressive crisis during his years with him, which Plotinus himself, according to Porphyry's own account, helped him overcome by recommending a recuperative journey to Sicily. His master's editor and biographer, Porphyry systematically organised Plotinus's scattered writings into the six Enneads, each divided into nine treatises — hence the name, 'groups of nine' — a thematic arrangement of his own devising that has since determined how posterity has read and studied Plotinian thought, prefacing them with a Life of Plotinus that constitutes one of the most valuable philosophical biographical sources of all antiquity. Philosophically, Porphyry leaned toward a more rationalist, less theurgic interpretation of Neoplatonism than that later developed by his own pupil Iamblichus, and his Isagoge, a brief introduction to Aristotle's logical categories, would become, through Boethius's influential Latin translation and commentary, one of the most widely studied logical texts of the entire European Middle Ages, serving as the direct starting point of the famous medieval controversy over the nature of universals that would divide realists and nominalists for centuries. Also the author of a now-lost treatise Against the Christians, considered one of the most sophisticated and erudite philosophical critiques of Christianity in all antiquity — known mainly through fragments preserved by Christian authors who refuted it, and later systematically burned by imperial order — Porphyry also wrote On Abstinence from Animal Food, a treatise defending vegetarianism with ethical and metaphysical arguments of notable sophistication for its time. His philosophical synthesis exerted decisive influence both on later Neoplatonism and, through medieval Latin and Arabic translations, on Christian scholasticism and Islamic philosophy.