Liber decretorum

The Liber decretorum, commonly known as Gratian's Decree, is a foundational collection of nearly 3,800 texts on church discipline and regulation compiled by the monk Gratian around 1140. This work was crucial for the study of canon law, serving as the primary text for university lectures and commentaries.12

Gratian's Decree aimed to harmonize apparent contradictions within existing church rules, drawing on Roman law and the writings of Church Fathers. It became the first part of the Corpus Juris Canonici, the comprehensive body of canon law, and influenced official codifications in 1917 and 1983. The study of these texts led to the development of "decretists" and "decretalists," scholars who commented on and interpreted canon law.1234