Gratian (died ca. 1155) is known as the father of canon law. His book on the laws of the Catholic Church revolutionized the study of canon law and was the single greatest authority on the subject until the 20th century.
Gratian was a monk in the Camaldolese congregation of the Order of St. Benedict. Hardly anything is known about his life. He was one of those historical figures whose works completely hide their persons. He was a lecturer at the monastery of Saints Felix and Nabor in Bologna in Italy at the time when that city was beginning to be widely known as a center for the study of law. The Catholic Church then had no uniform law. Over the centuries popes had made legal decisions, councils had issued decrees, and Church officials throughout Europe had used their authority in various ways. Doctrine and theology were also considered as guides for conduct.
For a century before Gratian, scholars had attempted to collect all this material and put it in some kind of order, but no one had been really successful. Sometime in the 1140s, after years of study, Gratian completed a work in this field that was outstanding. It was easily the best handling of this difficult subject that the world had seen, and it quickly became the most important textbook on Church law for all of Europe.
Gratian called his work Concordia discordantium canonum (Harmony of Conflicting Canons). In its almost 3,800 chapters he collected decrees from the councils and the popes, extracts from Roman laws, statements from the Church Fathers, and theological opinions—material which had been used to regulate the life of the Church for 10 centuries. He arranged the material systematically, according to subject matter. But his greatest contribution was the way in which he applied the newly emerging techniques of logic and dialectics to resolve conflicting decrees. The texts Gratian collected often were in contradiction to each other. He was able to show that the conflicts were frequently caused by different ways of using the same terms and so were usually more apparent than real.
This was not just another collection of laws but a new kind of book altogether. It taught a way of interpreting the law and a way of making practical sense of it according to the needs of different situations. Although it was never officially adopted by the Church, "Gratian's Decrees," as his work was known, became the most important legal guide for popes, bishops, and ecclesiastical courts until it was finally replaced by a completely new code of canon law in 1917.
A good discussion of Gratian is in Brian Tierney, Foundations of the Conciliar Theory: The Contribution of the Medieval Canonists from Gratian to the Great Schism (1955). A detailed discussion of Gratian and his place in the history of canon law is in Robert W. and Alexander J. Carlyle, A History of Mediaeval Political Theory in the West (6 vols., 1909-1936). Short histories of canon law and information on Gratian can also be found in Amleto G. Cicognani, Canon Law (1925; trans. 1934), and in T. Lincoln Bouscaren and others, Canon Law: A Text and Commentary (1946; 4th ed. 1963).