Scrying
Gazing into a polished surface, such as a crystal, a mirror or a bowl of water, in order to see visions.
Also: crystal gazing, crystal ball, mirror gazing, catoptromancy
Scrying means looking into a reflective or clear surface until images appear. Water, polished stone, obsidian, mirrors and glass have all been used, in places from ancient Greece and Persia to the Aztec world. The crystal ball is mostly a Victorian symbol, though crystal spheres were used earlier. The Elizabethan scholar John Dee worked with the medium Edward Kelley in the 1580s, using a crystal and an obsidian mirror that are now in the British Museum. Modern fortune-tellers keep the glass ball as a stage prop. Psychologists connect scrying to the visions that arise when the eyes stare at a blank field for long, and study it with the ganzfeld effect, which produces such images without any outside source.