The Decretum Gratiani, also known as the Concordia discordantium canonum or Concordantia discordantium canonum or simply as the Decretum, is a collection of canon law compiled and written in the 12th century as a legal textbook by the jurist known as Gratian. It forms the first part of the collection of six legal texts, which together became known as the Corpus Juris Canonici. It was used as the main source of law by canonists of the Roman Catholic Church until the Decretals, promulgated by Pope Gregory IX in 1234, obtained legal force, after which it was the cornerstone of the Corpus Juris Canonici, in force until 1917. In the first half of the 12th century Gratian, clusinus episcopus, probably a jurist of the ecclesiastical forum and a teacher, rubricator at the monastery of Saints Nabor and Felix (according to the Bolognese Odofredus Denariis [13th century]) and starting from the 18th century believed to have been a Camaldolese monk, composed the work he called Concordia discordantium canonum, and others titled Nova collectio, Decreta, Corpus juris canonici, or the more commonly accepted name, Decretum Gratiani, a living text, characterized by multiple editorial stages. He did this to obviate the difficulties which beset the study and the forensic application of practical, external theology (theologia practica externa), i.e., the study and the forensic use of canon law. In spite of its great reputation and wide diffusion, the Decretum has never been recognized by the Church as an official collection. The so-called vulgata or vulgate version (an advanced editorial stage) of the Decretum is divided into three parts (ministeria, negotia, sacramenta). The first part is divided into 101 distinctions (distinctiones), the first 20 of which form an introduction to the general principles of canon law (tractatus decretalium); the remainder constitutes a tractatus ordinandorum, relative to ecclesiastical persons and function. The second part contains 36 causes (causæ), divided into questions (quæstiones), and treat of ecclesiastical administration, procedural issues and marriage.