The essence-energies distinction, a central principle in Orthodox theology, was first formulated by Gregory of Nyssa and developed by Gregory Palamas in the 14th century in support of the mystical practices of Hesychasm and against Barlaam of Seminara. It stands that God's essence (, ousia) is distinct from God's energies, his manifestations in the world, by which men can experience the Divine. The energies are unbegotten or uncreated. They were revealed in various episodes of the Bible: the burning bush seen by Moses, the Light on Mount Tabor at the Transfiguration. Palamas […] taught that the ascetic endeavor of fasting and prayer, particularly the practice of the Jesus Prayer according to the teachings of the hesychastic Fathers, prepares one to receive the grace-filled light of the Lord, which is like that which shone on Mt. Tabor at the Lord's Transfiguration. In other words, if God wills, according to one's striving, one can partake of divine blessedness while still on this sinful earth.