The scion of a noble Anatolian family, St. Gregory was born, probably at Constantinople, c. 1296. After his father's death, he became a monk, as did several members of his family. He entered a monastery on Mt. Athos and followed the rule of St. Basil. He lived on Athos in solitude for most of the following twenty years. In the 1330's, he began to defend the practice of hesychasm against the attacks of people like Barlaam of Calabria, who denied, among other things, that the light of Tabor which hesychasts experience is the uncreated light. Athough the 1341 council of Constantinople upheld Gregory's teachings about theosis, he was excommunicated in 1344. Three years later, he was consecrated bishop of Thessaloniki. Because hesychasm had come to have political as well as theological associations, the choice was not popular, and he entered his see with the aid of the Byzantine emperor. The Turks captured Gregory in 1354 and kept him captive for a year. He died in 1359. Gregory believes that although God is ultimately unknowable, man can experience his energies through the sacraments and mystical experience, which are possible because of the Incarnation of Christ. The practice of the Jesus prayer opens one to God's energies.