PLOTINUS (A.D. 204–270), the most important representative of Neoplatonism, was born of Roman parents at Lycopolis in Egypt. At Alexandria he attended the lectures of Ammonius Saccas (q.v.), the founder of the system, until 242, when he joined the Persian expedition of Gordian III., with the object of studying Persian and Indian philosophy on the spot. After the assassination of Gordian in 244, Plotinus was obliged to take refuge in Antioch, whence he made his way to Rome and set up as a teacher there. He soon attracted a large number of pupils, the most distinguished of whom were Amelius, Eustochius and Porphyry. The emperor Gallienus and his wife Salonina were also his enthusiastic admirers, and favoured his idea of founding a Platonic Commonwealth (Platonopolis) in Campania (cf. Bishop Berkeley’s scheme for the Bermuda islands), but the opposition of Gallienus’s counsellors and the death of Plotinus prevented the plan from being carried out. Plotinus’s wide popularity was due partly to the lucidity of his teaching, but perhaps even more to his strong personality. Assent developed into veneration; he was considered to be divinely inspired, and generally credited with miraculous powers. In spite of ill-health, he continued to teach and write until his death, which took place on the estate of one of his friends near Minturnae in Campania.
Under Ammonius Plotinus became imbued with the eclectic spirit of the Alexandrian school. Having accepted the Platonic metaphysical doctrine, he applied to it the Neo-Pythagorean principles and the Oriental doctrine of Emanation (q.v.). The results of this introspective mysticism were collected by him in a series of fifty-four (originally forty-eight) treatises, arranged in six “Enneads,” which constitute the most authoritative exposition of Neoplatonism. This arrangement is probably due to Porphyry, to whose editorial care they were consigned. There was also another ancient edition by Eustochius, but all the existing MSS. are based on Porphyry's edition.
The Enneades of Plotinus were first made known in the Latin translation of Marsilio Ficino (Florence, 1492) which was reprinted at Basel in 1580, with the Greek text of Petrus Perna. Later editions by Creuzer and Moser (“Didot Series,” 1855), A. Kirchhoff (1856), H. F. Muller (1878–1880), R. Volkmann (1883–1884). There is an English translation of selected portions by Thomas Taylor, re-edited in Bohn’s Philosophical Library (1895, with introduction and bibliography by G. R. S. Mead).
On Plotinus generally see article in Suidas; Eunapius vitae sophistarum, and above all the Vita Plotini by his pupil Porphyry. Among modern works, see the treatises on the school of Alexandria by J. F. Simon, i. (1845), and É. Vacherot (1846); A. Richter, Ueber Leben und Geistesentwicklung des Plotin (Halle, 1864–1867); T. Whittaker, The Neoplatonists (1901); A. Drews, Plotin und der Untergang der antiken Weltanschauung (1907); E. Caird, Evolution of Theology in the Greek Philosophers (1904), ii. 210–257; Rufus M. Jones, Studies in Mystical Religion (1909). A detailed account of Plotinus’s philosophical system and an estimate of its importance will be found in the article Neoplatonism, the works above referred to, and the histories of philosophy. For his list of categories, see Categories; also Logos; Mysticism; Magic.