Hesychia means stillness, and the tradition is precise about what it does not mean: not emptiness, not trance, and not the absence of thought as an achievement, but attention resting in the heart with the prayer running under it. The fourteenth-century controversy is the sharpest thing the tradition has said about religious experience. Barlaam of Calabria mocked the Athonite monks for claiming to see the uncreated light of Tabor and for their bodily technique; Gregory Palamas defended them by distinguishing God's essence, which is unknowable, from God's energies, which are genuinely God and genuinely encounterable. Councils in Constantinople in 1341 and 1351 backed Palamas, and the essence–energies distinction became standard Orthodox theology and a real point of divergence from Western scholasticism, which never accepted it. Practically, the warnings matter more than the theory: teachers spend most of their time telling beginners not to pursue experiences.