In a series of specially commissioned essays, an international team of scholars examine both Platonism's metaphysical principles (the One or the Form of the Good and the Indefinite Dyad: the principles that account for unity and multiplicity) and the tradition's role as a source for ethical and political principles. In honor of Lloyd Gerson's remarkable contribution to Platonic scholarship, the full breadth of the tradition has been explored: from Plato's own manipulation of the wisdom that preceded him via his students in the Old Academy, Speusippus and Aristotle, and on to the Middle Platonic (Alcinous) and Neoplatonic (Plotinus, Proclus, Damascius) phases. An extensive section on Christian Platonism examines the Platonic appropriations of Cyril of Alexandria, as well as the great mediator of Plato in the Latin West, Marsilio Ficino, while the volume traces the influence of Platonic principles up to Heidegger. Key topics in this volume include time and eternity, the origin of evil, the planetary orbits, the status of nature, and theurgy. This Festschrift includes Gerson's intellectual autobiography in the light of Platonic principles, particularly as a justification for libertarianism.