Ulrich Horst is known primarily in the English-speaking world for his groundbreaking studies of the history of papal infallibility. However, in the last twenty years, he has produced studies on the mendicant orders, and the theology of Thomas Aquinas, which have complemented his research into the doctrine of infallibility. Sadly, none of these studies have received an English-language review. Evangelische Armut und Kirche (1992) traced the conflict among the secular clergy, the Dominicans (especially Aquinas) and Franciscans over poverty with a focus on consequent developments in ecclesiology. Evangelische Armut und päpstlishes Lehramt (1996) followed this same debate through the Franciscan battle with Pope John xxii. In two recent books Horst outlines the dispute between the secular clergy and the friars at the University of Paris over the papal privileges for the mendicants. He shows how this debate shaped both Aquinas's view of the episcopacy in the Church (Bischöfe und Ordensleute, 1999), and Aquinas's argument for the elevated status of the mendicant (especially Dominican) way of life (Wege in die Nachfolge Christi, 2006).

Horst's latest monograph, Dogma und Theologie: Dominikanertheologen in den Kontroversen um die Immaculata conceptio, returns to a subject which he first addressed in his book, Diskussion um die Immaculata conceptio im Dominikanerorden (1987). While his earlier work focused on the Dominicans in Spain in the sixteenth and seventeeth centuries, this new book treats the long international Dominican defensive against the Immaculate Conception. The book is structured primarily by devoting a section to each of twelve Dominican theologians from Aquinas in the thirteenth century through to Francisco de Araújo in the seventeeth, although at least another dozen theologians are treated briefly, while some like Vincent Bandello receive greater attention. Such chronological breadth allows Horst to shine as the expert he is in both the medieval and early modern periods. However, Horst's argument is essentially the same in both books: the Dominicans' theological methodology, not their mariology, isolated them in a posture of defence. They believed that the most important sources of theological doctrine were the Bible and the church Fathers, while the Immaculate Conception was (out of necessity) argued from liturgical practice, approved private revelation (for example St Bridget of Sweden's Revelations), and the sensus fidelium. As the Immaculate Conception continued to gain support among kings, prelates and people, the Dominicans were forced to respond, first in Catalonia in the 1380s, then in northern Italy after the definition (1439) of the doctrine by the Council of Basle. Some Dominicans, like Vincent Bandello, preacher of the Lombardy campaign, scoffed at the opinions of the ‘vulgar’, and denied that these new sources possessed any value. In response to the intervention of the Franciscan Pope Sixtus iv in favour of the liturgy of Mary's Conception in 1477, the Dominicans of the sixteenth century moderated, and some abandoned, their opposition. For example, the Dominican Cardinal Cajetan acknowledged that liturgy and piety were acceptable sources for doctrine, as long as they were in accord with Scripture and the Fathers – a position that still allowed him to oppose the doctrine.

In giving the unsung history of the losing side in this debate, Horst has written something like the opposite of a history of the development of doctrine, a genre that can too easily veer into Whig history. Historical theology such as Horst's is a warning to historians of Christian doctrine that methodology can be as important as theological content, and careful study of the losing side can enrich our understanding of the development of doctrine.

Like all Horst's works mentioned here, Dogma und Theologie suffers in that the index includes only names of persons, and the bibliography fails to spell out abbreviations of journals and encyclopedias. However, such matters are very minor, when we are so fortunate to have another definitive work from the learned Ulrich Horst.

Ulrich Horst works in a long tradition of scholarship within the Order of Preachers, an earlier phase of which has been made accessible by the publishing of Medieval Irish Dominican studies. Taking a collection of articles originally published in an obscure Irish monthly without references, Hugh Fenning op, editor and author of the preface, has compiled an index, more than 400 footnotes, a bibliography of the primary sources used by the author, Benedict O'Sullivan, and the latest secondary literature to produce a very fine text in book form.

Each of O'Sullivan's studies receives a chapter in the book; however, the book might be best considered as three distinct sections: (1) the foundation of individual Dominican houses; (2) what might be called the everyday life of the friars – personnel, architecture and, especially, income; and (3) the governance of the Irish houses within the international Order of Preachers. O'Sullivan takes the thirty-nine medieval foundations in chronological order, attempting to locate the precise year of the foundation and the identity of the founder. He can often only proffer an educated guess as to the identity of many of the founders because of the scarcity of medieval records following suppression of Irish religious houses in the sixteenth century. For a general overview of the growth of the Dominicans in medieval Ireland, this section is tedious; the only major conclusion drawn is that the friars were imported and endowed overwhelmingly by the Anglo-Normans, not by the native Irish aristocracy. And yet the scholar of individual foundations must begin here, benefiting from the editor's corrections, citations of primary sources and references to the most recent research, including short histories of eight of the houses recently written by Fenning. The second section, the most engaging, provides the best published history of the long-lost domestic arrangements of the friars, income from funerals, donations for building and liturgy, royal munificence and the institutionalisation of alms solicitations – the primary means of support for the friars. The third section is a history of the friars' faltering attempts to create an Irish province distinct from the province of England. Because of the opposition of the pope and the English king, the new province only took form with the 1536 dissolution of the English province. Regrettably, O'Sullivan does not explain how the lack of provincial status affected the history of the Irish Dominicans.

Fenning notes that Dominican bishops, the Observants, and the studium, could have benefited from more attention from O'Sullivan. I would add to that list preaching and literary activity, which would require the study of other sources, if they survive, besides the documentary records and the chronicles. Nevertheless, Hugh Fenning has done a great service to scholars by editing and footnoting these studies. They are certainly a worthy starting-point for the much needed comprehensive study of medieval Irish Dominicans.