THE BRITISH MUSEUM has a number of objects associated with the Elizabethan mathematician, astrologer and magician John Dee (1527-1608/9). Dee was one of the most learned men of his time, but later in life he became interested in psychic phenomena. He worked with a medium, who would see visions in ‘shew-stones’, polished translucent or reflective objects which Dee used as tools for his occult research.