Stephan Dusil has written a complex and significant narrative about structural changes in canon law and legal knowledge in the High Middle Ages, based on tedious textual and manuscript research. The length itself will put some readers off, but the work is made more digestible thanks to thorough introductions and conclusions to each chapter. Dusil operates within a theoretical framework that ties together Recht (law), Wissen (knowledge), and Ordnung (organization or system) as he traces the transition from one type of organization of legal knowledge to another. Along the way, he deals with major figures in the history of canon law (e.g., Burchard of Worms, Ivo of Chartres, and Gratian) together with lesser-known figures and collections (e.g., Bonizo of Sutri and the Collection in 74 Titles).

Across his introduction and six chapters, Dusil maps out how legal knowledge became transformed from something preserved in canonical collections, which served as storehouses of knowledge of various individual laws (c. 1000), to something woven together in a complex system in which every part is related to every other (c. 1215). He presents no neat linear progression. Rather, he gives full attention to personal agency and the pull-and-tug of innovations and traditional methods in the forging of something genuinely new. The pivotal player in the narrative remains Gratian, but Dusil gives a nuanced portrayal of the Decretum in its two major recensions. The first was far more innovative, but was not a simple watershed. Dusil's careful historical work, not just in pre-Gratian canonical collections but also in works of the late eleventh and early twelfth century that foreshadow various aspects of Gratian's textbook, brings out a more complete context for Gratian's work than is often appreciated. Gratian adopted methods from the trivium and assumed a genre more like a tractatus; these methods and genre formed the necessary basis to accomplish what he did. After all, Dusil argues, a mere collection of canons, even if prefaced with an interpretive prologue such as Ivo of Chartres's, could not be the basis of the transformation of legal knowledge.

Dusil develops that argument in the first three chapters before coming to Gratian in chapter four. Focusing on the issues of papal primacy and clerical celibacy as test cases throughout, he presents the legal knowledge evident in various canonical collections and in the writings of several different intellectuals. This legal knowledge could be complex, organizing individual canons in new ways and sometimes creating new legal knowledge on issues such as papal primacy through clever textual interventions or new rubrics that could turn specific historical statements into generalized legal norms. Nonetheless, it was limited in scope. Some compilers conceived of new modes of relating canons into a system; they presented their gedachte Ordnung (“conceptualized organization”) in prologues that gave readers a theory for how to relate one text to another. Yet, this gedachte Ordnung could not be applied to earlier collections or implemented to weave earlier canons into a workable system of canon law. Too much was left to individual readers. Chapter five establishes that, although some texts after Gratian returned to creating storehouses of knowledge, Gratian's textbook proved to be the foundation necessary for the generation of a new type of legal knowledge in which every law has its place in clear relationship to others, and a true system of canonical jurisprudence could emerge.

Dusil's work contributes to a trend in historical canon law scholarship that is re-narrating Gratian's place in a traditional divide of the field into pre-Gratian, Gratian, and post-Gratian scholars and scholarship. Borrowing the chronology of medieval studies more generally, Dusil has taken the long twelfth century, and gone back even earlier, in order to trace the historical changes of interest to him. Most originally, Dusil studies texts not just in terms of their “original” content but in terms of their manuscript reception and later appearances. Thus, he thinks about Burchard's Decretum not just as a single early-eleventh century text; he also examines later manuscript copies of it and pores over their marginal glosses and notes to see whether later commentators could form a system of legal knowledge on its basis (they apparently could not); he also observes how decretists returned to Burchard's text to fill in gaps that they noted in Gratian's Decretum as they were creating a complete canonical system. The history of canon law can no longer be told as a succession from one figure or collection to the next; Dusil has given an excellent example of the type of scholarship that acknowledges and explains a much more complicated, intertwined reality. Those looking for a simple narrative will not be satisfied with Dusil's book; those looking for the honesty of historical messiness will be.