“All told, this is an excellent piece of scholarship that brings to life the work and influence of a leading theorist in early modern medicine. Shackelford sheds clear light on how the Galenic tradition of medical practice was gradually overthrown in this period, and how chemistry emerged—albeit slowly—as the foundation of a new medical tradition.”

David Boyd Haycock, London School of Economics

“Shackelford’s study cuts across many boundaries. It is, of course, a much-needed account of Severinus and his systhesis of Paracelsian thought. For some readers it will also serve as an introduction to the meaning of Paracelsianism in the late sixteenth and early seventeenth centuries. However, in addition, the author examines this influence in many national settings, creating a survey of the key figures of European chemical philosophy. Historians of medicine have always had an interest in early modem developments, but Paracelsian studies have been relatively uncommon. This book is a welcome exception and should be considered required reading for anyone interested in that period.”

Allen G. Debus | Bulletin of the History of Medicine

“An excellent study of one of the most important Paracelsians, and much more besides. In writing the first book-length study of Severinus, a Paracelcian expositor who was so successful that his own name came to be used in an adjectival form (Severinian), Jole Shackelford has not only demonstrated the inadequacy of current historiography but also started us off on the way to its revision. Shackelford’s intellectual biography of Severinus places him firmly in his historical context, and in particular has much to say about the contemporary scene in Denmark. . . . Shackelford’s book will prove to be an essential source for scholars interested in Tycho and his context. With regard to Tycho’s alchemy, it has much more to offer than previous biographies devoted entirely to the great Danish astronomer. The rich account of Severinus’s education and career, told alongside those of his close friend, Johannes Pratensis (1543-1576), and of Thycho, will also prove indispensable for those interested in the fortunes of Paracelsianism in the universities of Northern Europe, and in the royal courts. Shackelford’s remit is not confined to Severinus himself and his immediate surroundings, however. It also embraces the nature and extent (in both space and time) of his influence throughout Europe, first of all as a commentator who was able to make sense of Paracelsus’s idiosyncratic teachings, and subsequently as the embodiment of what effectively came to be seen as Severinianism. Here again Shackelford provides a feast of incidental information on other thinkers who drew upon Severinus’s work.”

John Henry | American Historical Review