John Dee (1527-1608) was a noted English mathematician, astronomer, astrologer, geographer, occultist, and consultant to Queen Elizabeth I. He also devoted much of his life to alchemy, divination, and Hermetic philosophy. Dee straddled the worlds of science and magic just as they were becoming distinguishable. One of the most learned men of his time, he had lectured at the University of Paris when still in his early twenties. John was an ardent promoter of mathematics, a respected astronomer and a leading expert in navigation, having trained many of those who would conduct England"s voyages of discovery (he coined the term "British Empire"). Dee was an intensely pious Christian, but his Christianity was deeply influenced by the Hermetic and Platonic-Pythagorean doctrines that were pervasive in the Renaissance. He believed that mathematics (which he understood mystically) was central to the progress of human learning. His personal library at Mortlake was the largest in the country, and...