Studies of Gratian (about whom very little is known for sure other than that he taught in Bologna) and of his work have blossomed in the last twenty years. Anders Winroth's ground-breaking The Making of Gratian's Decretum (2004) demonstrated that the seminal canon law textbook of the Middle Ages, the Concordia discordantium canonum (The Harmony – a musical reference – of Discordant Canons, more usually referred to by the shorthand name of Decretum) exists in two recensions: an earlier, shorter version and a later version, showing greater emphasis on papal power and a greater familiarity with Romans law. Winroth posits two authors (conveniently referred to as Gratian 1 and Gratian 2), but Atria Larson, in her 2014 Master of Penance: Gratian and the Development of Penitential Thought and Law,Footnote ¹³ has suggested an even greater complexity of authorship and composition.

Larson's new book presents a critical edition of the lengthy treatise De penitentia (C 33 q 3 of the Decretum); there is an English translation (the first translation of this section in any modern language) on the facing pages. While many earlier scholars believed that the De penitentia was a later addition to the Decretum, Winroth has shown that it was added at an early stage in the ongoing composition and redaction of that work. More than 600 manuscripts of the Decretum survive; the standard, if somewhat inadequate, modern printed edition of the whole Decretum by Emil Friedberg (Leipzig, 1879) used eight. Larson employs seven, all from the twelfth century, and they are judiciously chosen. The introduction to this book deals mainly with textual matters and is somewhat brief, but Larson more than makes up for this with her earlier Master of Penance. Although several other scholars have attempted editions of parts of the earlier recension of the Decretum, no edition has been produced that is as long, as complete or as fully sourced as this one. It is a milestone of canonical scholarship and deserves to be pondered and celebrated.

Also published by the Catholic University Press in 2016 is John Wei's introduction to and reassessment of Gratian's (here, in Winroth's scheme, ‘Gratian 1’) use of the Bible and biblical exegesis, his penitential theology (here overlapping very nicely with Larson's work) and his handling of liturgy and sacramental theology. The surprise is not so much that Gratian can be considered a theologian, since in the middle of the twelfth century the two disciplines had not yet become clearly separated from each other either by their subject matter or their methodology, but that Gratian can be seen as incorporating so much into the Decretum that was later relegated to, or claimed by, theology alone.

Wei is a master of the sources and does a superb job not only of reviewing Gratian's own sources, both theological and canonical, but also of distinguishing different emphases of the first and second recension. He declares Gratian 1 to be the more ‘radical’ regarding both the sacraments and the liturgy, while the redactor of the second recension (‘Gratian 2’, who may, or may not, have been the same person) was more conservative. Some of the discussion of the dating of the work can be difficult to follow for non-specialists, but the rewarding romp of the chapter on the ‘canon law of magic’ more than makes up for this. Wei thus shows that the two recensions differ not only in their knowledge and use of Roman law, which has been recognised since Winroth's original work, but also in their theological outlook. This book admirably advances the study of both mediaeval law and mediaeval theology.