The series Heresy and Inquisition in the Middle Ages has nicely balanced monographs with essay collections. Inquisition and Knowledge, 1200–1700, its latest addition, derives from a conference in 2018 at the University of York, and gathers papers by a multinational group of medievalists and early modernists. “Knowledge” here takes many forms: how clerics discovered, created and shaped, or disseminated knowledge about heresy; how, what, and why we now know about medieval inquisitions; and how others in the past acquired such knowledge and what they did with it. Inquisition and Knowledge is divided chronologically, with part one's eight essays concerning the Middle Ages and five essays on the early-modern period in part two. For the purposes of a review, a fruitful way to divide the volume is by interest and approach: that is, by what kind of relationship between “inquisition and knowledge” is being examined and proposed.

Some essays concern the content of medieval antiheretical texts: what we can know about heresy and inquisition through them, and what their authors knew. Jessalyn Bird argues, via liturgical sermon collections, that the preaching of Paris masters more commonly addressed heresy than has previously been assumed. Alessando Sala argues for the importance of two formal components of Pope Gregory IX's letters, the arenga (preamble) and the narratio (summary of context that led to papal response) in establishing lasting biblical imagery for heresy, however unreliable they may have been about the reality of heresy. Two chapters, by Reima Välimäki and by Adam Poznanski, treat the Celestine monk and inquisitor Peter Zwicker. Välimäki offers a manuscript history, edition, and translation of Zwicker's anti-Waldensian De vita et conversacione. Like Sala on Gregory IX, Poznanski treats the formalities of rhetoric. Here, the focus is on the strategies that Zwicker deployed in his anti-Waldensian treatise, Cum dormirent homines, in order to persuade. Poznanski argues that Zwicker's treatise was practical, demonstrating the persistence of persuasion even amid the coercion of inquisition. Irene Bueno examines the treatment of Eastern-Orthodox Christians in the antiheretical works of Benedict of Alignan, Guido Terreni, Alvarus Pelagius, and Nicholas Eymeric. As in her other work, Bueno usefully emphasizes the “role of the papal court of Avignon as a key intellectual hub” in universalist considerations of heresy (136).

Another general theme is practice on the ground of real-world inquisitors. Jörg Feuchter examines the irony-laden career of Nepos of Montauban, who served as assistant and scribe for inquisitions, and as secular judge. But he also assisted in defense. Feuchter notes that while Nepos only redacted the Liber fugitivus with whose authorship he has been credited, this work, the “declared intention” of which “is to provide the accused with instruments to neutralise [inquisitors’] attacks,” still sits strangely on his career (74). Pawel Kras casts a fresh eye on Dominican inquisitor John of Schwenkenfeld's investigation in 1332 of sixteen “cowled nuns” in Silesia, an investigation strongly colored by the Council of Vienne's condemnation twenty years earlier of the so-called “Heresy of the Free Spirit.” Richard Kieckhefer revisits his influential European Witch Trials: Their Foundations in Popular and Learned Culture, 1300–1500 (1976), revising its thesis that “sorcery was a datum of popular belief, while diabolism was introduced by learned élites, particularly inquisitors” (195). With illustrations from specific trials, Kieckhefer now suggests a few qualifications, including the clergy's own credulity, accused persons who accused others, “regional difference,” and lessons learned from post-1976 research on false confessions.

A few essays treat the transmission into the early-modern period of medieval inquisitorial ideology and knowledge about heresy. Shelagh Sneddon and Peter Biller treat the Doat collection of the Bibliothèque Nationale de France, composed of seventeenth-century copies of southern-French documents gathered by Jean de Doat as pertinent to the Crown. The collection contains several volumes of inquisition material, and Biller and Sneddon were attached to the University of York's research project on Doat volumes 21–24. Sneddon's chapter focuses on the scribal introductions, in French, to the copied Latin documents, arguing that they evince much interest in naming elites; display little knowledge of or interest in heresy; and can misunderstand and mislead readers about the content of copied texts. Biller offers a “close-up picture” of what Jean de Doat encountered when in 1668 he searched for documents at the Dominican convent in Toulouse (274). This included the order's historians who belonged to it, most famously Jean-Jacques Percin, author of the controversial Monumenta conventus Tolosani, who liberally borrowed from his colleague Antonin Réginald.

More specifically, other essays detail how “knowledge” about, and derived from, medieval heresy and inquisition was applied to early-modern Protestant–Catholic confessional debates. Harald Bollbuck considers the “counter-church history” of sixteenth-century Lutheran reformer Matthias Flacius Illyricus. Flacius used inquisitorial registers and manuals to posit medieval heretics as antecedents of Lutherans, in part as a means to deny accusations of Protestant innovation. Flacius “advocated an ideology of truth witnesses that would historically legitimise the correctness of his own theology” (236–237). Like Bollbuck, Luc Racaut examines an early-modern appropriation of the medieval past for present ends, arguing that the “‘Cathars as Protestants’ myth” did not arise until the French Wars of Religion. Their violence evoked, for both Protestants and Catholics, the Albigensian Crusade. Michaela Valente also considers “myth,” seeking to “deconstruct” the Roman Inquisition, noting that “criticisms [of it] were motivated above all by [its] creeping jurisdictional usurpation,” while the ferocity of Gian Pietro Carafa (the future Pope Paul IV), tasked with reorganizing the inquisition, also attracted hostility (322). A legitimizing response by inquisitors and supporters, through various texts, was to argue for the Roman Inquisition's compatibility and continuity with Christian faith and tradition.

Inquisition and Knowledge has no bibliography, and scholars are only indexed if mentioned in the volume's body. Careful attention to footnotes is then necessary. There are several images from printed books, including print versions of medieval manuscript texts. The utility of these images is not always obvious, but they raise interesting questions about how medieval knowledge was quite literally repackaged, in early-modern print culture's new environment of knowledge as business. We might get excited that the title page of Guillaume Catel's Histoire des Comtes de Tolose features a clergy-friendly image of shepherd and sheep, until we realize that this was Pierre Bosc's printer's mark, used for everything (278). As Inquisition and Knowledge makes clear, printing enabled not only the recording, but also the remixing, of medieval knowledge about heresy and inquisition. What does it mean that such knowledge transformed into a market commodity?