"John Dee (13 July 1527 – 1608 or 1609) was an Anglo-Welsh mathematician, astrologer and occultist, and an advisor to Queen Elizabeth I. He spent much time on alchemy, divination and Hermetic philosophy. He advocated turning England's imperial expansion into a "British Empire", a term he is credited with coining. o 21st-century eyes, Dee's activities straddle magic and modern science, but the distinction would have meant nothing to him. He was invited to lecture on Euclidean geometry at the University of Paris while still in his early twenties. He was an ardent promoter of mathematics, a respected astronomer and a leading expert in navigation, who trained many who would conduct England's voyages of discovery. Dee amassed one of England's biggest libraries. His scholarly status also took him into Elizabethan politics as an adviser and tutor to Elizabeth I and through relations with her ministers Francis Walsingham and William Cecil. He tutored and patronised Sir Philip Sidney, his uncle Robert Dudley, 1st Earl of Leicester, Edward Dyer, and Sir Christopher Hatton.

His Mortlake library was the largest in the country before it was vandalized, and created at enormous, sometimes ruinous personal expense; it was seen as one of the finest in Europe, perhaps second only to that of De Thou. As well as being an astrological and scientific advisor to Elizabeth and her court, he was an early advocate of colonization of North America, envisioning a British Empire stretching across the North Atlantic. Dee promoted the sciences of navigation and cartography. He studied closely with Gerardus Mercator and owned an important collection of maps, globes and astronomical instruments. He developed new instruments and special navigational techniques for use in polar regions. Dee served as an advisor to English voyages of discovery, and personally selected pilots and trained them in navigation. He believed that mathematics (which he understood mystically) was central to human learning. The centrality of mathematics to Dee's vision makes him to that extent more modern than Francis Bacon, though some scholars believe Bacon purposely downplayed mathematics in the anti-occult atmosphere of the reign of James I. Although Dee's understanding of the role of mathematics differs much from ours, its promotion outside the universities was an enduring achievement. For most of his writings, Dee chose English, rather than Latin, to make them accessible to the public. His "Mathematical Preface" to Euclid was meant to promote the study and application of mathematics by those without a university education, and was popular and influential among the "mechanicians": a growing class of technical craftsmen and artisans. Dee's preface includes demonstrations of mathematical principles that readers could perform themselves without special education or training."

https://en.wikipedia.org/wiki/John_Dee