In lecture three, we turn to Aristotle’s metaphysics, focusing on “being as being” and the question of why anything exists at all. We explore his theory of substance as form–matter composites, his concept of the unmoved mover as pure actuality, and how this connects to his ethics, where contemplation is the highest human activity. The lecture concludes with his psychology in De Anima, where the soul is the organizing principle of living beings, and humans uniquely possess a rational soul that enables both practical and theoretical reason.