John Dee straddled the worlds of science and magic just as they were becomingdistinguishable. One of the most learned men of his age, he had been invited tolecture on advanced algebra at the University of Paris while still in his earlytwenties. Dee was an ardent promoter of mathematics and a respectedastronomer, as well as a leading expert in navigation, having trained many ofthose who would conduct England's voyages of discovery.Simultaneously with these efforts, Dee immersed himself in the worlds of magic,astrology and Hermetic philosophy. He devoted much time and effort in the lastthirty years or so of his life to attempting to commune with angels in order tolearn the universal language of creation and bring about the pre-apocalypticunity of mankind. A student of the Renaissance Neo-Platonism of Marsilio Ficino,Dee did not draw distinctions between his mathematical research and hisinvestigations into Hermetic magic, angel summoning and divination. Instead heconsidered all of his activities to constitute different facets of the same quest:the search for a transcendent understanding of the divine forms which underliethe visible world, which Dee called "pure verities".In his lifetime Dee amassed one of the largest libraries in England. His highstatus as a scholar also allowed him to play a role in Elizabethan politics. Heserved as an occasional adviser and tutor to Elizabeth I and nurturedrelationships with her ministers Francis Walsingham and William Cecil. Dee alsotutored and enjoyed patronage relationships with Sir Philip Sidney, his uncleRobert Dudley, 1st Earl of Leicester, and Edward Dyer. He also enjoyedpatronage from Sir Christopher Hatton.