Plotinus has been neglected for a long time, especially in the English speaking world. However, in recent years he has been increasingly recognized as one of the most important, rigorous and original thinkers in Antiquity. This course will offer an overview of Plotinus' thought, devoting particular attention to his metaphysics, epistemology and his conception of the natural world. By reading a series of treatises from the Enneads, we will analyze Plotinus' position on many fundamental issues: the relation between unity and multiplicity and being and non-being, his theory of Intellect and his answer to the Skeptic challenge, his conception of matter, evil and physical objects, and his notion of vertical causality. One of the aims of this course will be to show how Plotinus' philosophy represents a first fundamental rupture in the history of metaphysics.