Plotinus is the greatest philosopher in the 700 year period between Aristotle and Augustine. He thought of himself as a disciple of Plato, but in his efforts to defend Platonism against Aristotelians, Stoics, and others, he actually produced a reinvigorated version of Platonism that later came to be known as "Neoplatonism". In this volume, sixteen leading scholars introduce and explain the many facets of Plotinus' complex system. They place Plotinus in the history of ancient philosophy while showing how he was a founder of medieval philosophy.