At a crucial moment in his intellectual formation, C.S. Lewis began doctoral work on the Cambridge Platonist Henry More (1614-1687). This research did not lead to degree but Lewis’ encounter with Cambridge Platonism at the early stages of his philosophical and religious development exercised an important and lasting influence on his thought. His Augustinian-like conversion to Christianity, like the Bishop of Hippo before him, involved a series of moments but ultimately turned on an encounter with the ‘books of the Platonists’, books in this case composed, not in ancient Rome, Greece or Egypt, but in Cambridge in the seventeenth century. Lewis’ conversion, in his words, ‘from “popular realism” to Philosophical Idealism; from Idealism to Pantheism; from Pantheism to Theism; and from Theism to Christianity’ was made possible by a Platonising vision of the moral life, a vision that insisted upon an objective and transcendent moral good, reflected in the human soul and seen most clearly in the co-inherence of Imagination and Reason. Moral insight and the spiritual action that follows from it ultimately depend on love, for Lewis, a topic and theme that motivates all of his major scholarly, apologetic, philosophical, and literary writings. This paper will argue that his debt to the Cambridge Platonists and the tradition of Christian Platonism more broadly comes out most clearly in the way he thinks about the unifying nature and particular forms of love.