The evolution of the Concordia discordantium canonum or Decretum of Gratian has been a topic of great interest in recent years. Atria Larson focuses on one part of the larger whole, the Tractatus de penitentia. It is a portion of Causa 33 q. 3, which is found toward the end of the causae, the second and longest part of the collection. Larson argues on the basis of manuscript evidence that a form of the De penitentia was part of the causae from early on. It was not, however, formatted like a collection of canons. Instead, it had the continuous flow of a treatise. Only slightly later was the content divided into seven Distinctions, possibly by the early canonist Paucapalea. The author also indicates the instances in which texts added to the De penitentia later interrupt the flow of the original text. In addition, Larson suggests that we not stop with Anders Winroth's original argument that there were two versions of the Decretum, possibly not compiled by the same person. We are dealing instead with a collection in flux even after Winroth's second version was completed.
Larson's book is divided into two parts. The first presents the manuscript evidence for the original De penitentia and then outlines the text itself. Each of the first four Distinctions, which are concerned with the theology of penance, receives a thoroughly-documented chapter. These four Distinctions address larger issues like the weight to be put upon either contrition or absolution as most important factor in the forgiveness of sins. That discussion reflects the influence of Anselm of Laon and his school even in twelfth-century Italy. (One of the most interesting of Larson's arguments, based on shared ideas and methods of argument, is that Gratian studied with Anselm or one of his students.) The remaining three distinctions, more concerned with to pastoral practice, are covered in a single chapter. A major constituent part of these Distinctions was the De vera et falsa penitentia, falsely attributed to Augustine of Hippo. The author also addresses certain passages elsewhere in the Decretum which deal with penance in depth. One of the most significant of these deals with the penitential discipline to be imposed on a priest who falls into a grave sin but repents (Distinction 50), including whether he could be promoted to higher office. Promotion of such a priest was to be forbidden, even after he did penance and was absolved. Also treated at length is the exception to episcopal authority in a case of excommunication, when the person under censure is repentant and in danger of death (C. 26 qq. 6-7): a priest can absolve if a bishop cannot be reached in time to offer release. The De penitentia is foundational to the treatment of these and other pastoral issues in the Decretum, providing a theological orientation behind discussions of penitential practice. The author identifies Gratian's approach to his work not just as that of a teacher but that of a reformer, trying to remedy the ignorance of too many priests.
The second part of the book deals with Gratian's influence. The most important part of this section addresses the use of the Decretum in Peter Lombard's Sentences, the chief theological textbook after the Bible itself in the medieval universities. The Lombard made more use of the De penitentia than of any other nearly contemporary book concerned with penance. He adapted its texts rather than merely copying them, especially when advancing his own ideas about the importance of contrition in the forgiveness of sins. These adaptations are illustrated by parallel passages from Gratian and the Lombard. Appendix B documents these borrowings and adaptations in Book IV of the Sentences. The early Decretists made some use of the De penitentia, but most were not particularly interested in the more theoretical issues Gratian had treated. Only Huguccio of Pisa wrote a full commentary on this portion of the Decretum, offering his own opinions about penitential issues. Larson shows, however, that Omnibonus, in his compact revision of the Decretum, also made truly creative use of the De penitentia. (See also Appendix C.) However, theologians, including Peter the Chanter, did employ the Decretum in their discussions of penance. Likewise, Bartholomew of Exeter used the De penitentia in his penitential. Vacarius and Alan of Lille used the text in their refutations of theological errors. This section concludes with an argument that the De penitentia was part of the background of the decretals of Alexander III and Innocent III. The latter grounded certain of his sermons in the same milieu. Appendix D illustrates the use made by Celestine III of the De penitentia in his decretal Cum non ab homine. Even where not quoted directly, the De penitentia is found, in Larson's painstaking analysis of the texts, in the background of much of twelfth-century thought on the sacrament of penance. The Conclusion connects the Decretum, directly and indirectly, to the growing body of texts addressing penitential issues in a wider intellectual context, a new branch of law, the ius penitentiae.
Atria Larson's book casts light on Gratian's own intellectual identity. It is too easy to separate theologians from lawyers looking backward from the present, treating the Decretum as a work of jurisprudence. In Gratian's lifetime there was no such hard and fast division between disciplines. The book fits Gratian and his collection into a larger intellectual context in which the School of Laon was linked via Gratian's Bologna to Peter Lombard's Paris. In that context, Gratian is not so much a lawyer as a disciplinary theologian, teaching clergy how to understand their ministry and perform the role of confessor in a more informed manner.