The Decretum Gratiani or Concordia discordantium canonum (in some manuscripts Concordantia discordantium canonum) is a collection of Canon law compiled and written in the twelfth century as a legal textbook by a jurist (perhaps) named Gratian. It forms the first part of the collection of six legal texts, which became known as the Corpus Juris Canonici and which retained legal force in the Roman Catholic Church up until Pentecost Sunday, May 27, 1917, when the a revised Code of Canon Law (Codex… (More on Decretum)