HESYCHASTS, a quietistic sect which arose, during the later period of the Byzantine empire, among the monks of the Greek church, especially at Mount Athos, then at the height of its fame and influence under the reign of Andronicus the younger and the abbacy of Symeon (i o u acrrai, from i crvxos, quiet) . Owing to various adventitious circumstances the sect came into great prominence politically and ecclesiastically for a few years about the middle of the i4th century. Their doctrine and practice is obviously related to certain well-known forms of Oriental mys ticism, according to which in an attitude of entire bodily immobil ity and concentration a divine light was shed within the soul. This was maintained to be the pure and perfect essence of God Him self, that eternal light which had been manifested to the disciples on Mount Tabor at the transfiguration. The doctrine was taken to affirm two divine substances, a visible and an invisible God, and much controversy ensued until in 1351 the "untreated light" of Mount Tabor was established as an article of faith for the Greeks, who ever since have been ready to recognize it as an additional ground of separation from the Roman Church.
See article "Hesychasten" in Herzog-Hauck, Realencyklopddie (3rd ed., 1900) , where further references are given.