Neil Tarrant, <i>Defining Nature's Limits: The Roman Inquisition and the Boundaries of Science</i> Chicago: University of Chicago Press, 2022. Pp. 288. ISBN 978-0-226-81942-6. $45.00 (cloth).

Defining Nature's Limits contributes to an expanding field of scholarship that examines the relationship between religion and science in medieval and early modern Europe by re-evaluating how the Catholic Church shaped scientific knowledge.Neil Tarrant argues that 'the inquisition of magic' (p.9), as he calls it, played an instrumental role in establishing the boundaries between orthodox and heterodox knowledge of the natural world.Although this demarcation arrived at a crucial crossroad with the establishment of the Roman Inquisition in the sixteenth century, Tarrant convincingly contends that one must venture into the Middle Ages to reveal its origins.By focusing on the Dominican order and its members' primary role in the medieval and Roman inquisitions, he reconstructs the long history of intellectual debates around magic.He shows that a complex and multifaceted discussion over the status of what he calls the 'operative arts'forms of learned magic such as astrology and geomancyshaped the Church's approach to superstitious and heretical magic and influenced what came to be considered licit scientific knowledge.The book's first part deals with the medieval origins of inquisitorial prosecution of magic.Tarrant situates it within the papacy's burgeoning attempts to fortify its power and enforce orthodoxy in Western Europe between the eleventh and fourteenth centuries.He shows how novel perceptions of learned magic as potentially heretical evolved with the Church's broader attempts to persecute heretics and how the papacy relied on the mendicant orders (including the Dominicans) to achieve this goal.The most significant argument advanced in this part of the book describes the emergence of a theoretical debate concerning the nature of the operative arts.Tarrant argues that, before the eleventh century, canon law largely portrayed magic as forbidden since it involved the intercession of demons.This notion was challenged in the thirteenth century by Dominican theologians, and most notably Thomas Aquinas, who proposed that learned magic was legitimate as long as its operation was natural and not demonic.According to Tarrant, this development changed both the understanding of learned magic and the focus of inquisitorial procedures: it rendered questionable not only the intent of practitioners, but even the operative arts themselves, whose innate functions became subject to inquisitorial scrutiny.This idea was not, however, promptly adopted by the Church and incorporated into inquisitors' work.Fourteenth-century theologians, particularly the influential Dominican inquisitor Nicholas Eymerich, persisted in proscribing magic that involved forbidden ritualistic elements while misinterpreting Aquinas's works.The book's second part studies the inquisition of magic in the fifteenth and sixteenth centuries.Tarrant once again positions this development within a renewed struggle for