Among the papers of Hugh Trevor-Roper, who died in 2003, was a manuscript to which he had repeatedly turned for more than thirty years, but never published. Attracted by the diverse life and vivid personality of Sir Theodore de Mayerne (1573-1655), the most famous physician in Europe of his time, Trevor-Roper pursued him across national and intellectual frontiers to uncover the details of his extraordinary life. Exploring an array of English and European sources, Trevor-Roper reveals the story of the pioneering Swiss Huguenot doctor who mixed medicine with diplomacy, with political intrigue, with secret intelligence, and with artistic interests at the courts first of Henry IV of France and then of James I and Charles I of England. A true 'renaissance man', Mayerne's interests were broad, and due to considerable conspiratorial talent, he became a participant in bluff and intrigue at the highest levels. The most ambitious and perhaps the most original of all Trevor-Roper's books, written in his luminous prose, this is a major work of political and intellectual history that presents a whole period in a fresh and vivid light.