Scrying is a form of divination in which the practitioner gazes at a reflective surface such as a crystal ball, although any reflecting surface can be used: a mirror, a pool of water, polished stone or burnished metal. In general, the term for inducing visions by gazing into a clear depth is crystallomancy. The word scrying is derived from the archaic English verb descry, meaning to see or to perceive, and an object that can be used for scrying is known as a speculum, or a shewstone.
The images seen in the reflective surfaces by a skilled scryer have been considered to have occult or religious significance since at the least the time of the Ancient Greeks. The travel writer Pausanias described a spring at Taenarum in the Peleponnese that was supposedly able to reveal events occurring in the nearby harbour. Chapter 44 of the Old Testament’s Book of Genesis contains a brief description of Joseph’s silver chalice, which it says he used for drinking and for divination;[a]Joseph was a slave who rose to become vizier, the second most powerful man in Egypt after the Pharaoh. the text is generally agreed to date from between the 7th and 5th centuries BCE.
Scrying has also been used to recover lost or stolen objects, the earliest English account of which dates from 1467. A Yorkshireman named William Byg confessed to earning a living by using a crystal ball to discover lost property, and was convicted of heresy by an ecclesiastical court. His punishment was to walk to York Minster carying a placard proclaiming him to be a sorcerer.
The images seen in the reflective surfaces used in scrying may be hallucinations, with the crystal ball, for instance, serving as a convenient screen onto which they can be projected.
Such images may alternatively be a form of perceptual illusion, as demonstrated by the psychologist Gianovanni G. Caputo in a paper published in the journal Perception. Subjects were asked to sit in front of a mirror in low light conditions, looking at their own reflection, and after ten minutes were asked to report what they had seen.[b]Scrying using a mirror is sometimes known as catoptromancy. Almost half reported seeing “fantastical and monstrous beings”, and ten per cent saw the face of a dead parent. Caputo suggests that this as yet incompletely understood effect might be linked to a fault in the process of facial recognition in lighting conditions that cause a lack of stability in the edges, shading and outlines of facial features; he called this phenomenon the strange-face-in-the-mirror illusion.