Aristotle

Lived: 384 BC–322 BC

Aristotle was born in Stagira in 384 BC, studied at Plato's Academy for twenty years, then founded his own school, the Lyceum, in Athens. His extant corpus covers logic, metaphysics, natural philosophy, biology, ethics, politics, and rhetoric — a systematic mapping of human knowledge unmatched in antiquity.

For Catholic Christian psychology, Aristotle's most consequential contributions are the doctrine of the soul as the form of the body (De Anima), the account of moral virtue as habituation of rational appetite (Nicomachean Ethics), and the teleological framework that orders human action toward eudaimonia — flourishing understood as activity in accord with reason. Through Aquinas's appropriation, these became core resources of the Catholic Christian Meta-Model of the Person.

Medieval scholastics referred to him simply as "the Philosopher." Modern virtue-ethics psychology — including the work of Alasdair MacIntyre, Martha Nussbaum, and Christopher Peterson — draws directly on his ethical framework.