Robert Boyle (1627-91), one of the seminal figures in the origins of modern science, yet a complex and tortured personality, has been the subject of much scholarly attention in recent years. Here, Michael Hunter, the acknowledged expert on Boyle, makes use of much hitherto unpublished material to offer a novel and distinctive view of the man. Hunter's re-evaluation of Boyle focuses on an elucidation of his religious life, and particularly his concern with matters of conscience, which Boyle pursued with an obsessiveness that contemporaries characterised as `scrupulosity'. This arguably lay at the root of the convoluted intellectual personality revealed in many aspects of Boyle's ideas and activities. In addition, by studying works that Boyle wrote but never published, Hunter illustrates the extent to which he was constrained by his fear of being at odds with groups like the medical profession and with public opinion more generally. In these essays, Boyle emerges as a troubled figure, plagued by religious doubt, ambivalent about magic, and convoluted in his relations with the wider world.Michael Hunter is Professor of History, Birkbeck College, University of London, and chief editor of the definitive edition of Boyle's Works (1999-2000) and Correspondence (forthcoming).