It remains the case in English-language scholarship on the Reformation that the study of the many individuals who contributed to this intellectual and theological movement continues to be dominated by the two major figures of the day – Martin Luther and John Calvin, and those closely associated with them (such as Philip Melanchthon or Theodore Beza respectively). With regard to the Swiss Reformation, Ulrich Zwingli has received much more detailed study of late thanks to Bruce Gordon’s masterful biography of the Zuricher, but the German-speaking Swiss Reformation had many other significant contributors to it, and it could be argued that the study of them, and of Reformers from South-West Germany with whom they had so many interconnections (Martin Bucer and Wolfgang Capito especially), continues to lag behind with respect to translations of works and correspondence, and thus substantial studies of them in English. It is the latter gap in resources that the present volume admirably fills for the further study of Zwingli and his fellow Swiss Reformer, Johannes Oecolampadius of Basel, drawing upon volumes vii–xi of Huldreich Zwinglis Sämtliche Werke.

In addition to the correspondence itself (183 letters in total), the volume provides a lengthy introduction, beginning with biographical sketches setting each Reformer in their respective city – especially useful for understanding Oecolampadius, who is much the lesser-known of the two Reformers. Following this is a brief account of their personal relationship which, contrary to the accepted view of leader and follower (Zwingli and Oecolampadius, respectively), leads the editors to suggest there was more equality between the two as co-labourers in a common task. Rounding out the biographical sketch is a brief account of the work of these Swiss Reformers with Martin Bucer and Wolfgang Capito, the Reformers of Strasbourg and South-West Germany more broadly, and thus the wider world of the early Rhenish Reformed tradition.

The introduction also provides very useful attention to the practice of letter-writing in the sixteenth century. Letters were often written not only with the person addressed in each letter in view, but also with a broader audience as well – these are not private letters, but a semi-public correspondence. Because of the potential that this correspondence might fall into the wrong hands, it is fascinating to find that the Reformers used codewords to protect themselves.

In one sense, the task of the editors/translators was straightforward, since the extant correspondence had already been gathered in the Sämtliche Werke. Yet a close reading of the letters reveals that numerous of them have gone missing. The originals of those that are in this collection are all in good condition. It is interesting to learn that for all the work of editors of the originals, many of these do not have a precise date that all can agree upon, though the order in which they were written is fairly clear. The introductory considerations conclude with a brief discussion of the challenges of translation. This is with reference not only to the work of the present translators, but also to the efforts of Zwingli and Oecolampadius in handling Greek and Hebrew. Interestingly, Oecolampadius sought to be as faithful as possible to texts in the original language, whereas Zwingli was keen to make sure his ‘target audience’ was in view (the difference between formal versus dynamic equivalence).

The correspondence begins with Oecolampadius’s first letter to Zwingli on 10 December 1522 (letter 258), and concludes with his last letter to Zwingli on 30 September 1531 (letter 1,285). It is curious that the last letter by Zwingli was dated 4 June 1531 (letter 1,217), which is followed by eight letters from Oecolampadius to Zwingli ending with the Baseler’s letter of 30 September (i.e. letter 1,285). Indeed, only fifteen of these collected letters are from Zwingli to Oecolampadius, leaving the vast majority of them being from Oecolampadius to Zwingli, which could imply less equality between the two than the editors suggest, though they do observe that this apparent imbalance is characteristic of all of Zwingli’s correspondence – overall, only some 21 per cent of the letters in the Sämtliche Werke are written by him. Each letter is accompanied by notes relating to the text of each letter, followed by historical or explanatory details, and each entry is completed with notes as to where the original and/or a copy is located.

Given that the years covered by this collection were critical to the development and course of the Lord’s Supper controversy, the work of Harris and van Dijk is especially important for any reassessment of that crucial Reformation debate between Lutherans and Zwinglians. The role played by Zwingli and Oecolampadius in cooperation with the Strasbourg Reformers is seen through the lens of Basel and Zurich, but this makes one wish that the collection could have been expanded to include the correspondence of Bucer with these two Swiss Reformers – though this is not to fault the editors for not producing a different book.

The volume also contains brief biographies of principal figures with whom Zwingli and Oecolampadius interacted, and in every case references are included to where more can be read on them. Also useful are the several indices and bibliographies to primary and secondary works. This volume is very well-produced, and will be a major resource for the study of the Swiss and South-West German Reformations during the first decade of the wider Reformation.