On June 20, 1584, Edward Kelley received an extended vision of the four Enochian Watchtowers and the hierarchies of spirits connected with them. This Great Vision of the Watchtowers was central to the Enochian system of magic. John Dee considered it to be so vitally important, he engraved it onto a large medallion of solid gold, which is still preserved in the keeping of the British Museum, along with most of Dee's other magical instruments.