Gemistus Pletho
Greek science and literature remained alive in the Byzantine world, and Byzantine philosophy drew heavily on Plato, Aristotle, and the Neoplatonists, even if it was now Christian in tone. In the 7th century, John of Damascus produced a three-part encyclopedia containing in its third part a systematic exposition of Christian theology. In the 9th century Photios, the Patriarch of Constantinople, collected many works by ancient writers, and studied Aristotelian logic, and his pupil Arethas commentated on works by Plato and Aristotle. By the 11th and 12th centuries there was a growing interest in the teaching of philosophy, and figures such as Michael Psellos, Eustratius of Nicaea, and Michael of Ephesus wrote commentaries on Aristotle. In the 13th and 14th centuries we have important philosophers such as Nicephorus Blemmydes and Theodore Metochites. An important figure was Gregory Palamas who developed a mystical movement known as Hesychasm, which involved the use of the noetic Jesus prayer to achieve a vision of the uncreated Light also called the Illumination or Vision of God. It was the Hesychast movement that caused a rift in the Christian East which led many philosophically minded individuals to go West. This migration played a critical role in the manifestation of the Renaissance in the West. Especially the role Barlaam of Calabria, who opposed Hesychasm, played in the formation of Roman Catholic theology in the West. The last great philosopher of Byzantium was Gemistus Pletho who felt that a restored Platonism could reverse the decline of the Empire. He was an important figure in the transmission of ancient philosophy to the West.