The career of the sixteenth-century English mathematician and natural philosopher John Dee (1527-1609) has played a significant role in recent historiographical debates about the relationship between magic and science in the early modern period. This collection of interdisciplinary essays, which addresses a wide range of Dee's diverse intellectual activities (including mathematics, astronomy, navigation, astrology, alchemy, cabala and "angel magic") seeks to enlarge the scope of this debate, as well as presenting new archival and bibliographical discoveries relating to Dee and his collaborators and colleagues. The essays in the volume present new views on the nature of Dee's various projects, as well as the uses to which he put the books and manuscripts in his library at Mortlake (one of the largest private collections in Elizabethan England).