A picture of a man and a real man share the name animal but not the definition. From namesakes Aristotle builds to ousia in its fullest sense: this man here, on which everything else depends, alone able to hold opposites by changing itself.
Aristotle distinguishes namesakes, true namesakes, and things named after something, then sorts things by whether they are said of a subject or present in one. He lays out the ten categories and defines ousia in its primary and secondary senses, ending with what belongs to ousia alone: receiving contraries by changing itself.
Terms in today's reading — psuche: the life in a living thing — what animates it · ousia: substance — what a thing most truly is
Glossary and more: DailyAristotle.com