If the Jesuit Martin Delrio (1551-1608) is remembered at all today, it is for his Disquisitiones magicae (1599-1600), a voluminous tome on witchcraft and superstition which was reprinted numerous times until 1755. The present volume recovers the lost world of Delrio's wider scholarship. Delrio emerges here as a figure of considerable interest not only to historians of witchcraft but to the broader fields of early modern cultural, religious and intellectual history as well. As the editor of classical texts, notably Senecan tragedy, Delrio had a number of important philological achievements to his name. A friend of the Flemish philosopher Justus Lipsius (1547-1606) and an enemy of the Huguenot scholar Joseph Scaliger (1540-1609), he played an important part in the Republic of Letters and the confessional polemics of his day. Delrio's publications after his admission to the Society of Jesus (the Disquisitiones included) marked a significant contribution to the intellectual culture of the Counter-Reformation. Catholic contemporaries accordingly rated him highly, but later generations proved less kind. As attitudes towards witchcraft changed, the context in which the Disquisitiones first emerged disappeared from view and its author became a byword for credulity and cruelty. Recovering this background throws important new light on a period in history when the worlds of humanism and Catholic Reform collided. In an important chapter, the book demonstrates that demonology, in Delrio's hands, was a textual science, an insight that sheds new light on the way witchcraft was believed in. At the same time, the book also develops a wider argument about the significance of Delrio's writings, arguing that the Counter-Reformation can also be seen as a textual project and Delrio's contribution to it as the product of a mindset forged in its fragile borderlands.