Late Byzantine philosopher and humanist; b. Constantinople, c. 1355 or 1360; d. Mistra, June 25, 1452. Apparently born George Gemistos, he was educated at Constantinople but as a youth spent considerable time at the Ottoman court in Brussa or Adrianople, where he studied occult arts and the teachings of Zarathustra (Zoroaster) with a Jewish savant named Eliseus. On the violent death of his mentor, Plethon, as he called himself, evidently in honor of Plato, moved to Mistra in the Peloponnesus, near Sparta, and opened a school of esoteric philosophy and religion. In 1413 he directed memoirs to Emperor Manuel concerning the affairs of the Peloponnesus and in 1414 another to the emperor's son Theodore, concerning the fortification of the Morean Isthmus, in which he proposed a complete reorganization of the civil and military society. In 1428 he was consulted by Emperor john palaeologus concerning the reunion of the Latin and Byzantine Churches and was brought to the Council of florence (1439) as one of the Greek theologians. He signed the decree of reunion, despite the fact that he later wrote an opposing treatise On the Procession of the Holy Spirit. While in Italy he presented the humanists with the tract Difference between Aristotle and Plato.
On his return to Mistra, Plethon published his chief work, Nomōn Syngraphē, in which he described a kind of political utopia. He proposed an idealized paganism built on elements of Neoplatonic philosophy: human felicity consists in the harmony between man's nature and the universe, of which man is only an element. Sin is but error; morality and religion can achieve only earthly, not heavenly, happiness; and in death, the soul returns to a spiritual, but not a supernatural, state and will exist in a sinless and happy condition.
Plethon's political philosophy was directed toward the complete reformation of life in the Peloponnesus, whose population he considered of pure Hellenic strain. In the reconstitution of society, he proposed three classes: the cultivators of the land, the merchants, and the imperial functionaries. The first two were to support the state with their products and money; the third, with military service. Among his many writings Plethon produced a treatise On Virtues, several tracts on the teachings of Zarathustra, a commentary on the Analytics of Aristotle, a tract on the Incarnation and on Latin theology, and orations for the death of the Princess Cleopas (1433) and the Empress Helen. His three books on the Laws contain a description of the liturgy of the new religion he desired to found. He was of original genius and had a strong influence on the Byzantine scholars who stimulated the Renaissance in Italy, but Plethon had no successors. His teachings were opposed by bessarion, who had been one of his pupils in Mistra, and his Laws were publicly burned by George Scholarius after he became patriarch of Constantinople as gennadius ii.
Bibliography: Patrologia Graeca, ed. j. p. migne, 161 v. (Paris 1857–66), 160:821–1020. s. p. lampros, ed., v. 3–4 (Athens 1926–30). b. kotter, Lexikon für Theologie und Kirche, ed. j. hofer and k. rahner, 10 v. (2d, new ed. Frieburg 1957–65) 8:561–562. e. stÉphanou, Dictionnaire de théologie catholique, ed. a. vacant et al., 15 v. (Paris 1903–50; Tables générales 1951–), 12.2:2393–2404. Échos d'Orient 31 (1932) 207–217. f. masai, Pléthon et le platonisme de Mistra (Paris 1956); Revue de l'Université de Bruxelles 10 (1957–58) 392–412. h. dÖrrie, Die Religion in Geschichte und Gegenwart, 7 v. (3d ed. Tübingen 1957–65), 2:1375–76. h. g. beck, Kirche und theologische Literatur im byzantinischen Reich (Munich 1959), 754–755. m. v. anastos, "Pletho's Calendar and Liturgy," Dumbarton Oaks Papers, 4 (1948) 183–303. j. p. mamalakes, Georgios Gemistos Plethon (Athens 1939), in Gr. d. j. geanakoplos, Greek Scholars in Venice (Cambridge, Mass. 1962) 35, 75, 85–86.