Neo-Platomsm, a system of philosophy and theosophy whose original seat was Alexandria, where it sprang up toward the end of the 2d century. Its founder was Ammonius Sac-cas, who was brought up by his parents in the Christian faith, but renounced it and became a Hellenist. He died A. D. 243. His most distinguished disciples were Plotinus, Longi-nus the philologist, and two Origens, one of whom surnamed Adamantius was the famous father of the church. About two centuries earlier Philo, an Alexandrian Jew, born probably a few years before Christ, had promulgated a system by which he sought to reconcile the philosophy of Plato with the teachings of Moses. He held that the Hebrew Scriptures contained an internal sense in which were hidden all the doctrines of the Greek philosophy. (See Philo Judaeus.) Ammonius endeavored to reconcile the doctrines of Aristotle with those of Plato, and both with Christianity, and hence his school was called eclectic. He taught that God is primarily essence, and secondarily knowledge and power, and that asceticism is the true way to attain to a knowledge of the infinite. Little however is known of his teachings, as he left no writings, and his disciples bound themselves not to divulge his doctrines.

Plotinus was the first to put the new philosophy into writing, and to teach it at Rome, where he went to live in 244. He taught that the One or the Good, which with Plato was the highest of the Ideas, is elevated above the sphere of the Ideas, and above all the objects of rational apprehension, and that the Ideas, to which Plato ascribed independent existence, are emanations from this One, the soul an emanation from the Ideas, and so on. The One, or the Good, is neither reason nor an object of rational cognition. From the excess of its energy it sends forth an image of itself. This image is Nous or mind. The Nous in turn produces as its image the soul which exists in it, as itself exists in the One. The body is in the soul and depends on it; but the soul is absolutely separable from the body, not only in its thinking power, but also in its lower faculties. It precedes and survives the body. The business of man is to return to God, whom he as a sensuous being has estranged from himself. The means for this return are virtue, philosophic thought, and above all the ecstatic intuition of God and the becoming one with him.

Prominent among the disciples of Plotinus was Porphyry, who died about 304. He appears to have taught more distinctly than his master the doctrine of the emanation of matter from the soul. He also maintained that the world was without beginning in time. He attacked Christianity, and especially the divinity of Jesus. Iamblichus, who died about 330, employed the Neo-Platonic philosophy in support of paganism, and relied more on Pythagorean speculations as to the mystical powers of numbers than on Platonic ideas. Among his disciples was the emperor Julian the Apostate. The attempt to overthrow Christianity and revive paganism failed, and the Neo-Platonists now applied themselves to scientific studies, and especially to commentaries on Plato and Aristotle. Proclus was the most important of these later writers. - Some writers give to Neo-Platonism a much wider scope than that of the school of Ammonius and his disciples. They include in it not only Philo-Judreus, but several of the Christian fathers besides Origen, as for instance Clement of Alexandria, Gregory Nazianzen, and Cyril of Alexandria. (See Alexandrian School).