In the history of metaphysics, Plato, Aristotle, and Plotinus hold a special place, both for the richness of their reflections and for the influence they have exerted on Western thought. Through a series of introductory lectures, alongside discussions and analyses of selected passages from these three authors, the seminar aims to delve into metaphysical themes that were explored in the ancient world and continue to hold significant relevance in the contemporary world. The texts for analysis will come from selected passages of Plato’s dialogues (specifically from Phaedo, Sophist, and Republic), Aristotle’s Metaphysics (books I, IV, VI, VII, and XII), and Plotinus’s Enneads (VI,9,1-5).