Hesychasts (Greek ἡσυχασταί, ἡσυχάζειν, to be quiet), a party of Eastern monks of the 14th century, on Mount Athos. They taught a refined and exaggerated mysticism, or quietism (q.v.), seeking "tranquility of mind and the extinction of evil passions by contemplation." They believed that all who arrive at the blessedness of seeing God may also arrive at a tranquility of mind entirely free from perturbation, and that all enjoying such a state may have visual perception of divine light, such as the apostles saw when they beheld His glory shining forth in the transfiguration. The monk Barlaam (q.v.), who afterwards became bishop of Gerace, during a visit to the East, learned the doctrines and usages of these quietistic monks, and attacked them violently. They were vigorously defended by Palamas, afterwards bishop of Thessalonica. The charges brought against them were not merely that they professed to seek and obtain a divine and supernatural light not promised in Scripture, but also that the means they used were fanatical and absurd. These means included contemplation, introversion, and ascetic practices; especially it was said that they were accustomed to seat themselves in some secret corner, and fix their eyes steadfastly upon the navel, whence they were called ὀμφαλόψυχοι. As the fruit of such contemplation, a divine light, they said, such as that which shone on Tabor, was diffused through their souls. Palamas defended this theory by making a distinction between the essence (οὐσία) of God and his activity (ἐνέργεια), asserting that the latter, though eternal and uncreated, is yet communicable. To the charge that they thus claimed directly to see God, inasmuch as this uncreated light must be either of the substance or of the attributes of God, they replied that the divine light radiated from God through ἐνέργεια, but was not God. The whole matter was brought before a council at Constantinople in 1341. and the decision tending favorably to the Hesychasts, Barlaam retreated to Italy. But his cause was taken up by another monk, George Acyndinus, who attacked the doctrine of Palamas and the usages of the Hesychasts. He also lost his case before a synod at Constantinople. After the death of the emperor Andronicus, however, who had favored Palamas and the Hesychasts, things took a different turn for a while in favor of the Barlaamites; but after the triumph of the emperor John Cantacuzenus, who favored the other side, a synod at Constantinople, in 1351, approved the doctrine of the Hesychasts, especially the distinction between οὐσία and ἐνέργεια, and excommunicated Acyndinus and Barlaam. The sources of information on these proceedings are the Historia of John Cantacuzenus (2, 39; 4,23, etc.), which is on the side of the Hesychasts; and the Historia Byzantina of Nicephorus Gregoras, which takes the other side. See Petavius, De Dogm. Theol. ,lib. 1, c. 12; Schröckh, Kirchengeschichte, 34:431; Mosheim, Church Hist. cent. 14:pt. 2, ch. 5; Gass, in Herzog, Real-Encyklop. 6, 52 sq.; Engelhardt, in Zeitschrift d. hist. Theol. 8:48; Gieseler, Church History, per. 3:§ 127; Bingham, Orig. Eccles. bk. 7:chap. 2, § 14; Dorner, Person of Christ, Edinb. translation, div. 2, vol. 1. p. 236. SEE MYSTICISM.