Divination with a mirror or another reflective surface is an ancient practice known as scrying. The term originates from the word ‘descry’, meaning ‘to catch sight of’. The design of this scrying mirror was very popular among early 20th-century English witches. This example once belonged to the witch Cecil Williamson. He warned that, if you gaze into it, ‘and suddenly see someone standing behind you, whatever you do, do not turn around’.