Abstract: Plato has been read as holding to a dualistic ontology that separates into two worlds the intelligible and the sensible by a seemingly unbridgeable gulf. This unbridgeability causes the greatest difficulty, for how can entities in ontologically separate worlds interact? This difficulty has typically led to solutions which deny ontological dualism and opt instead for a monism or a pluralism of idealism or of materialism. I shall contend, however, that a dualistic interpretation of Plato's philosophy is a misreading, that, in fact, Plato himself criticizes dualistic ontology, and further that Plato's dialectician employs a triadic method in which contraries are held together in the pursuit of a unitary whole.