Scrying is the practice of gazing into a reflective or translucent surface to receive visions, guidance, or knowledge of hidden or distant things. The tools are various, the polished crystal ball most famously, but also black mirrors (such as the obsidian mirror), still or darkened water (hydromancy), a flame or the embers of a fire, ink pooled in the palm, and polished stones or metals. The practitioner fixes the gaze on the surface and allows the eyes to relax, so that shapes, scenes, or symbols seem to form in or beyond it, which are then interpreted.
The practice is ancient and cross-cultural, water-gazing and mirror-gazing appear in the Greco-Roman world, in Mesopotamia, and across many folk traditions, and it had a notable place in Renaissance ceremonial magic: the Elizabethan scholar John Dee famously worked with a "shewstone" or crystal, through which his associate Edward Kelley reported the visions and angelic communications that produced the Enochian system. Psychologically, scrying is understood to work by providing an unstructured visual field, like clouds or inkblots, onto which the mind projects imagery arising from the imagination and the unconscious, a state aided by the light trance the steady gazing induces. As a discipline it thus functions as a technique for accessing intuitive or unconscious material through visual reverie, framed within the practitioner's tradition as the perception of spirits, distant events, or the future.