Gregory of Palamas was born ca. 1296 to a noble Anatolian family, probably in Constantinople. After his father died, he and two of his brothers became monks, and his mother, two of his sisters and several servants became nuns. Gregory entered a monastery on Mt. Athos and followed the Rule of St. Basil, living in solitude for most of the next 20 years. In the 1330s, he began to defend the hesychast practice, centered on a method of prayer used by monks in Byzantine monasticism—possibly linked to Buddhist techniques—that involved controlled breathing and posture to induce a vision of light, often compared to the light seen at Jesus’ transfiguration on Mt. Tabor. Hesychast comes from hesychia, which means “stillness” or “light.” Opponents of hesychasm denied that the light of Tabor, which hesychasts experienced, was the uncreated light of the Godhead. The breathing techniques to experience this uncreated light were dangerous, and if done improperly or done to excess, could cause physical and mental damage. Gregory’s defense of the reality of the monk’s prayer experience was called Palamism. He maintained that though God had an unknowable essence, the energies of God’s grace—a part of God—were knowable. Thus God could be experienced through sacraments and mystical experience. This was made possible by the incarnation of Christ. Palamism contrasted with Catholic theology, which maintains that God is ineffable and cannot truly be experienced. Hesychast, prayer, or Palamism, created controversy and conflict that drew in lay people and became quite political. A hesychasm party formed. The 1341 Council of Constantinople upheld Gregory’s teachings, and Palamism was officially adopted by the Orthodox Church. Gregory, however, was excommunicated in 1344. In 1347, he was consecrated bishop of Thessalonica, an appointment that required the aid of the Byzantine emperor, due to the controversy over Palamism. Gregory worked diligently to reconcile deep social and political divisions. In 1354, invading Turks captured Gregory and held him prisoner for a year. He died in 1359. Gregory left behind a large body of works, several of which are included in The Philokalia compilation. He is considered one of the great spiritual masters of Orthodox Christianity.