Porphyry

Porphyry was a Phoenician from Tyre who studied under Plotinus in Rome, edited his master’s treatises into the Enneads and wrote his life, and composed the fifteen books Against the Christians that the emperors ordered burned. The Isagoge, an introduction to Aristotle’s Categories explaining the five predicables, genus, species, difference, property and accident, was translated by Boethius and became the first text of logic in every medieval school, and its opening question, whether genera and species exist in themselves or only in the mind, began the debate over universals that occupied the Middle Ages. Thomas Aquinas College reads it in freshman year as the doorway to the Organon.