The British Museum has a number of objects associated with the Elizabethan mathematician, astrologer and magician John Dee (1527-1608/9). After his death, some of Dee's manuscripts passed into the hands of the antiquary Sir Robert Cotton (1571-1631), whose collection was one of the founding collections that formed the British Museum in 1753. The two smaller wax discs shown here are all that survive of the original four which are recorded in the Cotton manuscripts (now in the British Library) as having supported the legs of Dee's 'table of practice'. The larger one, the 'Seal of God' (Sigillum Dei) corresponds exactly with a drawing in Dee's manuscripts. It was used to support one of Dee's 'shew-stones', the polished translucent or reflective objects which he used as tools for his occult research. All three wax discs are engraved with magical names, symbols and signs.Annotations in the margins of the Cotton manuscript seem to indicate that one of Dee's stones was spherical, thus it has been thought that this sphere may be the 'Chrystallum' in which Edward Kelly, Dee's medium, saw his 'visions'. However, the Cotton provenance cannot be proven nor can the object be identified in the manuscript catalogues of Sir Hans Sloane's collection.The gold disc is engraved with the Vision of Four Castles, experienced during one of Dee's 'experiments' at Krakow in 1584.For information about Dr Dee's mirror, and a biography, see Related Objects and Information.