Academy the school established by Plato around 385 B.C. at his property outside Athens near the public park and gymnasium known by that name. Although it may not have maintained a continuous tradition, the many and varied philosophers of the Academy all considered themselves Plato’s successors, and all of them celebrated and studied his work. The school survived in some form until A.D. 529, when it was dissolved, along with the other pagan schools, by the Eastern Roman emperor Justinian I. The history of the Academy is divided by some authorities into that of the Old Academy (Plato, Speusippus, Xenocrates, and their followers) and the New Academy (the Skeptical Academy of the third and second centuries B.C.). Others speak of five phases in its history: Old (as before), Middle (Arcesilaus), New (Carneades), Fourth (Philo of Larisa), and Fifth (Antiochus of Ascalon). For most of its history the Academy was devoted to elucidating doctrines associated with Plato that were not entirely explicit in the dialogues. These ‘unwritten doctrines’ were apparently passed down to his immediate successors and are known to us mainly through the work of Aristotle: there are two opposed first principles, the One and the Indefinite Dyad (Great and Small); these generate Forms or Ideas (which may be identified with numbers), from which in turn come intermediate mathematicals and, at the lowest level, perceptible things (Aristotle, Metaphysics I.6). After Plato’s death in 347, the Academy passed to his nephew Speusippus (c.407–339), who led the school until his death. Although his written works have perished, his views on certain main points, along with some quotations, were recorded by surviving authors. Under the influence of late Pythagoreans, Speusippus anticipated Plotinus by holding that the One transcends being, goodness, and even Intellect, and that the Dyad (which he identifies with matter) is the cause of all beings. To explain the gradations of beings, he posited gradations of matter, and this gave rise to Aristotle’s charge that Speusippus saw the universe as a series of disjointed episodes. Speusippus abandoned the theory of Forms as ideal numbers, and gave heavier emphasis than other Platonists to the mathematicals. Xenocrates (396–314), who once went with Plato to Sicily, succeeded Speusippus and led the Academy till his own death. Although he was a prolific author, Xenocrates’ works have not survived, and he is known only through the work of other authors. He was induced by Aristotle’s objections to reject Speusippus’s views on some points, and he developed theories that were a major influence on Middle Platonism, as well as on Stoicism. In Xenocrates’ theory the One is Intellect, and the Forms are ideas in the mind of this divine principle; the One is not transcendent, but it resides in an intellectual space above the heavens. While the One is good, the Dyad is evil, and the sublunary world is identified with Hades. Having taken Forms to be mathematical entities, he had no use for intermediate mathematicals. Forms he defined further as paradigmatic causes of regular natural phenomena, and soul as self-moving number.
Polemon (c.350–267) led the Academy from 314 to 267, and was chiefly known for his fine character, which set an example of self-control for his students. The Stoics probably derived their concept of oikeiosis (an accommodation to nature) from his teaching. After Polemon’s death, his colleague Crates led the Academy until the accession of Arcesilaus.
The New Academy arose when Arcesilaus became the leader of the school in about 265 B.C. and turned the dialectical tradition of Plato to the Skeptical aim of suspending belief. The debate between the New Academy and Stoicism dominated philosophical discussion for the next century and a half. On the Academic side the most prominent spokesman was Carneades (c.213– 129 B.C.).
In the early years of the first century B.C., Philo of Larisa attempted to reconcile the Old and the New Academy. His pupil, the former Skeptic Antiochus of Ascalon, was enraged by this and broke away to refound the Old Academy in about 87 B.C. This was the beginning of Middle Platonism (c.80 B.C. – A.D. 220). Antiochus’s school was eclectic in combining elements of Platonism, Stoicism, and Aristotelian philosophy, and is known to us mainly through Cicero’s Academica. Middle Platonism revived the main themes of Speusippus and Xenocrates, but often used Stoic or neo-Pythagorean concepts to explain them. The influence of the Stoic Posidonius (135–50/51 B.C.) was strongly felt on the Academy in this period, and Platonism flourished at centers other than the Academy in Athens, most notably in Alexandria, with Eudorus (first century B.C.) and Philo of Alexandria (fl. A.D. 39).
After the death of Philo, the center of interest returned to Athens, where Plutarch of Chaeronia (A.D. c.45–c.125) studied with Ammonius at the Academy, although Plutarch spent most of his career at his home in nearby Boeotia. His many philosophical treatises, which are rich sources for the history of philosophy, are gathered under the title Moralia; his interest in ethics and moral education led him to write the Parallel Lives (paired biographies of famous Romans and Athenians), for which he is best known. After this period, the Academy ceased to be the name for a species of Platonic philosophy, although the school remained a center for Platonism, and was especially prominent under the leadership of the Neoplatonist Proclus (c.410– 85). See also MIDDLE PLATONISM, NEOPLATON- ISM , NEW ACADEMY , PLAT. P.Wo.