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Aristotle

A short treatise classifying the ways in which something can be said of a subject: substance, quantity, quality, relation, place, time, position, state, action and affection. It distinguishes primary substance, the concrete individual, from secondary substances, species and genera, and studies opposites, priority and motion. Through Boethius's Latin translation and Porphyry's Isagoge it was for centuries the first philosophy book a student read, and its doctrine of substance shaped the whole of medieval ontology.

Categories by Aristotle — full text · The Conscious Library