John Dee (July 13, 1527 - 1608 or 1609) was a prominent British mathematician, astronomer, astrologer, geographer, occultist, and advisor to Queen Elizabeth I. His life and work straddled the realms of science, magic, and mysticism, reflecting the Renaissance-era belief in the integration of these pursuits.

Dee was born in Tower Ward, London, to a Welsh family. His father, Roland Dee, was a mercer and minor courtier. Dee attended Chelmsford Chantry School and later St. John's College, Cambridge, where he was recognized for his abilities and became a founding fellow of Trinity College.

In the late 1540s and early 1550s, Dee traveled across Europe, studying and lecturing in Paris. He studied with Gemma Frisius and befriended the cartographer Gerardus Mercator. Dee returned to England with a significant collection of mathematical and astronomical instruments.

In 1552, Dee met Gerolamo Cardano in London, exploring topics such as perpetual motion machines and magical gems. He was offered a position at Oxford but declined, criticizing the emphasis on rhetoric and grammar over science and philosophy.

Dee became a member of the Worshipful Company of Mercers in 1555. He faced charges of treason and was examined by the Catholic Bishop Bonner but cleared his name. Dee later became an advisor to Queen Elizabeth I and played a role in selecting her coronation date.

From the 1550s through the 1570s, Dee provided technical assistance in navigation and ideological backing for England's voyages of discovery. In 1577, he published _General and Rare Memorials pertayning to the Perfect Arte of Navigation_, outlining his vision of a maritime empire and asserting English claims in the New World.

In the 1580s, Dee began focusing on the supernatural to gain knowledge. He sought to communicate with angels through a “scryer” or crystal-gazer. Dee initially struggled but found success with Edward Kelley, who became his assistant in spiritual conferences.

These sessions, conducted with intense Christian piety and periods of purification, resulted in the dictation of several books in a special angelic or Enochian language. Dee and Kelley traveled across Central Europe but faced difficulties, including a controversial order from an angel for Kelley and Dee to share their wives, which caused Dee significant anguish.

Dee returned to England in 1589 and faced further challenges. His library at Mortlake was ruined and his possessions stolen. In 1592, he became warden of Christ's College, Manchester, but struggled with widespread revulsion and contempt for his supernatural practices.

Dee spent his final years in poverty at Mortlake, passing away in late 1608 or early 1609.

- Mathematics and Navigation: Dee promoted the importance of mathematics and its application in navigation. He advised English voyages of discovery, developed new instruments, and trained navigators. - Hermetic Philosophy: Dee's work was influenced by Hermetic and Platonic-Pythagorean doctrines. He believed mathematics was central to understanding the divine and aimed to unify religious beliefs through his work. - Library: Dee's library was one of the largest and most significant in England, attracting many scholars and serving as a major center of learning.

Dee's reputation as a magician and his association with Kelley led to various myths and misconceptions. The publication of Dee's spiritual communications by Robert Cotton and Meric Casaubon in the 17th century contributed to his image as a deluded fanatic.

In the 20th century, historian Frances Yates re-evaluated Dee's contributions, highlighting his role as a serious scholar and emphasizing the integration of magic and science in his work. Dee's influence extended to navigation, cartography, and the promotion of mathematics outside the universities.

Several items associated with Dee are held by the British Museum: - Dee's Speculum or Mirror (an Aztec obsidian object) - Small wax seals used in Dee's practices - Large wax “Seal of God” - Gold amulet engraved with Kelley's visions - Crystal globe (provenance less certain)

In December 2004, a shew-stone and an explanation of its use were stolen from the Science Museum but were recovered shortly after.