This is the last book of a trilogy on the Roman Inquisition (2013, 2014) by Thomas F. Mayer, former professor of history at Augustana College, before his passing in January 2014. This book should be read along with his The Trial of Galileo 1612-33 (2012), which contains primary documents.

The Roman Inquisition contains seven chapters: the “Florentine Opposition,” in particular focusing on Galileo's Sunspot Letters of 1613 (chapter 1); “Formal Proceedings Begin Late 1614-February 1616” (chapter 2); “Precept of 26 February 1616” (chapter 3); “Legal Meaning of 1616” (chapter 4); pre-trial events 1630–1632 (chapter 5); “Second Phase of Galileo's Trial Begins” (chapter 6); and the sentencing (chapter 7). There is an appendix of frequency of precepts, 105 pages of notes, and a 7-page bibliography.

The leitmotiv of this excellent study is the precept of February 26, 1616 and its place in the events of 1616–1633. Mayer pays close attention to technical legal terms and inquisitorial procedure. The author describes the two stages of the Galileo trial largely as a narrative, with extended treatments of the main participants. He provides background on the use of the precept, the subject of much modern analysis.

Mayer wisely avoids speculation on the reasons for the hostility of Galileo's critics, such as N. Lorini, V. Maculano, R. Bellarmino (sometimes), A. and F. Barberini, and Pope Urban VIII (at least in the latter part of the second phase). He downplays the role of political factions, particularly the Dominicans and the Jesuits, both inside and outside the Inquisition. The author focuses on the symbiotic interaction between the heresy aspects of the charges, and the “precept theory,” which relates more to discipline, jurisdiction, and administration. In his introduction Mayer states straightaway that he will argue for the precept interpretation as against the heresy interpretation. He sticks to his promise and makes a powerful case. He shows how complex the proceedings became at every phase, and how the easily the trial could have moved in different directions. He does not condescend to refute the stereotypes that continue to shape the popular images of Galileo, the alleged martyr for science in the face of pope and dogmatic religion. The second stage was hardly the mock-trial of modern caricature. Ironically the dust jacket on the book descends to just the kind of simplistic nonsense that Mayer abhors: “Galileo undoubtedly stood at a watershed moment in the political maneuvering of a powerful church” (front cover advertisement; back dust cover refers to “one of history's most notorious verdicts”). There are no heroes or villains in Mayer's account, which does not ignore the defendant's missed opportunities (such as refusing counsel), alleged lying (183, 218) about his memory of the 1616 precept from the Holy Office, and naively relying on outside influence, such as the grand duke of Tuscany. Mayer is critical of previous renderings of the precept, especially those of Fantoli, Beretta, Pagano, and Speller, albeit he is quick to acknowledge their insights. He explains how inquisitorial procedure could be both exact in following its guidelines, and careless in ignoring them; both motivated by high principle, and subject to outside pressure; both adept in knowing the rules of juridical procedure, and arbitrary in their application; both legally competent yet amateurish in the court personnel's handling of the processo. Often the inquisitors assign different meanings to the precept, but not out of malice but out of ignorance of the law and precedent. Mayer shows how the early opposition to the Sunspot Letters became forgotten in the larger issue of whether the protagonist had violated the precept of 1616 with the publication of his Dialogue, which deals explicitly with the Copernican heliocentric universe.

If modern historians have often depicted the precept of 1616 in different ways, so did the officials of the tribunal. To add to the confusion about the term, scholars sometimes translate praeceptum (precetto) in various ways, such as injunction, citation, or warning. Mayer's unraveling of these different uses is masterful, referring to the decree registers to illustrate their meaning. Mayer's thesis is most forcefully advanced in chapter 6, with the key roles of Niccolini and Maculano. A nice touch is added with the allusion to Urban's more pressing problems in 1632–1633 (179).

Mayer's editors have not served him well. I counted over ten typographical errors. Many works cited in the notes are omitted in the bibliography. (One wonders why the important work of R. J. Blackwell on the Summarium was not engaged, although alluded to in the notes.) There are too many clichés and run-on sentences. Paragraph structure is weak, and the chapter conclusions are too brief, lacking transitions. The general conclusion could be expanded to assess the larger context of the 1616-1633 proceedings in the history of the Roman Inquisition, the papacy, turmoil in Italy, the 30 Years War, post-Trent theology, and then-current discussions about Copernicus and the scientific method.

Professor Mayer's book is professional research at its best. This masterpiece is a product of many decades of exacting scholarship. This final work of a truly great historian stands as a memorial to his distinguished career. His concentration on one facet of the trial of Galileo has contributed mightily to our understanding of the entire episode and the mechanism of the Roman Inquisition.