This is a well-planned and clearly-written book on an important subject: the ways in which theologians and other intellectuals defined “superstition” in the fourteenth and fifteenth centuries. Michael Bailey's main title may be confusing and impenetrable, but his subtitle, pointing to the “boundaries” of superstition, is apt and precise.

The book's introduction, setting out the relational nature of the term “superstition” and outlining its changing meanings, will be valuable for students, and remains thought-provoking for more advanced scholars. Briefly, the argument is that superstition was defined in terms of what it was not; in this period it was mostly not-religion, but occasionally it could be not-science, as it usually has been in modern times. Related terms are unpacked with care: magic, science, religion, and rationality, as well as more specialized terms like witchcraft, divination, and necromancy.

Bailey's sources are mainly theological texts, and he has ranged widely in his search for them. His eleven-page appendix of texts is a feat of scholarship, discussing location, authorship, and dating of each text, and citing important printed editions, either contemporary, near contemporary, or modern. Many texts remain in manuscript. Most are from France and Germany; Bailey largely excludes the region south of the Alps for unexplained reasons (17). Perhaps as a result, there is little in the book about the Renaissance; Bailey's own concerns are very much “late medieval,” and he worries (perhaps overmuch) about the shadow cast by Johan Huizinga.

The book's structure is simple enough. Chapter 1 deals with the millennium or so before 1300, in largely narrative mode, and Chapters 2 and 3 continue the narrative, in much more detail, to about 1400. There is then a bifurcation. Chapters 4 and 5 both cover the fifteenth century, but Chapter 4 is largely thematic, discussing a large number of writings worrying about popular superstition. Chapter 5 discusses the century's witchcraft writings, culminating in the Malleus Maleficarum of 1486. These demonological writings have been studied from numerous angles, but Bailey finds a fresh line of approach, focusing on what they said about how to counteract witchcraft. Was it legitimate to counter demonic hailstorms by casting hailstones into a fire in the name of the Holy Trinity? The Malleus argued that it was (218).

The concluding chapter is “Towards Disenchantment?” This looks forward to modern times. Bailey reviews the debate on modernity and “disenchantment,” outlines changes in the concept of “superstition” since 1500, and seeks (perhaps over-ambitiously) to argue that his late medieval writers have something distinct to contribute to the debate. These different purposes are not always signposted clearly, particularly when it comes to “rationality,” and Bailey's problematizing of “modernity” may lead unwary students into simplistic generalizations. There is a passage (248–249) that could lead them to conclude that late-medieval theologians were as “modern” as we are because they used rational argument–though Bailey himself, of course, says nothing as crude as that.

Late medieval scholars mostly worked within a framework established in earlier centuries. The pioneering theology of Augustine remained important, and thirteenth-century syntheses by William of Auvergne and Thomas Aquinas were never superseded. Indeed one of Bailey's overarching arguments is that fourteenth- and fifteenth-century writers failed, both individually and collectively, to produce a synthesis of their own. This may be surprising, since there was little open controversy about the main issues, merely variety about what to emphasize. The only clear debate in the book was between Pierre d'Ailly and Jean Gerson about astrology in the early fifteenth century, and even that was polite and muted. As well as debate, there was explicit uncertainty and the recognition of the possibility of future knowledge, as with Gerson on amulets (136). Such knowledge was most likely to come from scholastic reasoning rather than observation and experiment; these scholars were not modern. There was, however, an intriguing episode in the late fourteenth century when some scholars, particularly Nicolas Oresme, seemed to move towards defining “superstition” as a false understanding of the natural world (close to modern definitions of the term); this “might have become a dominant view, but did not” (96).

There has recently emerged a large body of scholarship in this general field, notably on witchcraft, some of it by Bailey himself. In the present book, like the late medieval authors whom he is studying, Bailey does not aim to be wholly innovatory, preferring to build upon, and to synthesize, this influential body of work. He pays generous tribute to Euan Cameron's recent overview, Enchanted Europe: Superstition, Reason, and Religion, 1250–1750 (New York: Oxford University Press, 2010). Bailey's thorough survey of the relevant texts, however, gives his own book value.

One significant message of the book is that fear of the devil's influence increased during the late Middle Ages. In the fourteenth century, this was most visible in concern about elite, political magic. In the fifteenth century, more writers turned to attacking popular “superstitions.” There was also a geographical shift: the fourteenth-century texts tended to come from France, while more of the fifteenth-century texts were from the German lands. As Bailey points out, this may have fed into the later intensity of witch-hunting in Germany.

Bailey's principal concern is with his writers' ideas themselves, but he is well aware that we would all like to know whether they also furnish information about real beliefs and practices, especially among the common folk. Were the superstitions condemned by Gerson and others real? Here, Bailey is cautious; often his writers repeated each other, or were simply vague. He might have consulted witchcraft trial records in order to pursue this question further, but what he has done is certainly commendable. It would now be fascinating to conduct a study of how the common folk themselves negotiated their magico-religious practices, how they conceptualized and explained actions of which they knew that the authorities might disapprove. Its potential to facilitate further research is one of many reasons why Bailey's book is coherent and satisfying.