Neoplatonism, a development of Plato's metaphysical and religious teaching, whose best-known representatives were Plotinus, Porphyry, Iamblichus and Proclus, was the dominant philosophical school of the later Roman Empire and has been a major influence of European and Near Eastern thought and culture ever since. Yet the school's philosophy is only now coming to be studied in detail by historians of philosophy, largely because of the difficulty of the Neoplatonists' writings and the lack of a good summary exposition. This defect has been remedied in this, the first full-length study of the school by a single author to appear for over half a century. Lloyd P. Gerson's new Foreword sets that contribution in context; he also provides an up-dated Bibliography.