John Dee (1527-1608/9) was an astrologer to Queen Elizabeth I and a philosopher who sought secret knowledge of the natural world. Dee observed the heavens; he argued for a reform of astrology based on accurate measurements of the motions of heavenly bodies; he developed a monad through which an alchemist could read nature; he highlighted the value of mathematics for studying the natural world; he tutored explorers in navigational techniques; he evaluated the Gregorian reform of the calendar; and he spoke with angels. He used every means at his disposal to understand the natural world, yet it was his angel conversations that most influenced Dee’s story and place in history. For centuries after his death, Dee was mentioned primarily as a sorcerer who had lost his way, but historians have recently reconsidered Dee’s work as part of a re-examination of early modern science.

I examine John Dee’s variety of approaches to understanding the natural world within the context of the activities of his contemporary natural philosophers, including Gerard Mercator, Gemma Frisius, Girolamo Cardano, Thomas Digges, Jofracus Offusius, Tycho Brahe, Johannes Kepler, Michael Maestlin, Simon Forman, and Robert Fludd. I consider Dee’s goals for understanding the natural world, the methods that he used to gain that knowledge, and the context in which he worked in an effort to uncover Dee’s scientific contributions and to suggest ways in which Dee’s activity might influence our understanding of the practice of early modern natural philosophy. Dee was a respected philosopher during his time, and his advancements in navigation and his application of mathematics to the study of the natural world were some of his most lasting influences in the development of science. At the same time, his introduction of a monad through which an adept alchemist could “read” nature was received positively in alchemical circles and adopted by other philosophers. I argue that Dee’s varied methodology of understanding the natural world was, indeed, common practice in the sixteenth century. Many of his contemporary philosophers were seeking the same goals and using some of the same methods of natural inquiry as John Dee.