Gratian's Decretum, completed around 1140, represents a monumental development in the history of canon law and Christian political theory. As the foundational text for a new, systematic approach to Church law, Gratian's work combined the ancient canons with innovative scholastic methods, reconciling contradictions and offering a cohesive legal framework. This Concordia discordantium canonum (Concordance of Discordant Canons) not only became the cornerstone...