Hesychasm became the centre of a major theological controversy in fourteenth-century Byzantium. The hesychast monks of Athos claimed that the practice could culminate in the vision of a divine, uncreated light, the same light, they held, that shone from Christ at the Transfiguration on Mount Tabor. Critics, led by the philosopher Barlaam, dismissed such claims and the accompanying bodily techniques of prayer as crude. The monk and later archbishop Gregory Palamas defended the hesychasts with a distinction that became Orthodox doctrine: between God's unknowable essence, which no creature can approach, and his "energies," the divine action and presence in which God is genuinely encountered and by which the human person is deified. The light of the vision, Palamas argued, is God's uncreated energy truly seen, not a created symbol.
The councils of the mid-fourteenth century vindicated Palamas, and his essence-energies distinction and the theology of theosis, the transformation of the human person by participation in the divine life, remain foundational to Orthodox thought. Hesychasm thus stands as both a method of prayer and the practical root of a whole theological vision, and its repetitive invocation invites comparison with the mantra and remembrance practices of other traditions while resting on its own distinctive Christology.