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 Juris canonici) was promulgated by Pope Benedict XV. (The Code became binding throughout the Western Church the Pentecost Sunday of the following year, 19 May 1918.)
Two Recensions of Gratian's Decretum
Thanks to Anders Winroth, we now know that the Decretum existed in two published recensions. The first recension dates to some time after 1139, while the second recension dates to 1150 at the latest. There are several major differences between the two recensions:
- the first recension is a more coherent and analytical work;
- the second recension places a much greater emphasis on papal primacy and power;
- the second recension includes Roman Law extracts taken directly from the Corpus Juris Civilis, whereas the first recension does not display any great familiarity with Roman jurisprudence.
These differences have led Winroth to conclude that Roman Law was not as far developed by 1140 as scholars have previously thought. He has also argued that the second recension was due not to the original author of the first recension (whom he calls Gratian 1), but rather another jurist versed in Roman law. However, Winroth's thesis of two Gratians remains controversial.
This field of inquiry is hampered by our ignorance of the compiler's identity and the existence of manuscripts with abbreviated versions of the text or variant versions not represented by Winroth's two recensions, for instance, the manuscript St. Gall, Stiftsbibliothek, 673 (=Sg), which some have argued contains the earliest known version (borrador) of the Decretum, but which other scholars have argued contains an abbreviation of the first recension expanded with texts taken from the second recension.
Gratian's sources were Roman law, the Bible, the writings of (or attributed to) the Church Fathers, papal bulls, the acts of church councils and synods. In most cases, Gratian did not obtain this material from a direct reading of the sources, but rather through intermediate collections. Thanks to the research of modern scholars - in particular, Charles Munier, Titus Lenherr, and Peter Landau - we now know that Gratian made use of a relatively small number of collections in the composition of most of the Decretum, these being:
- Anselm (II) of Lucca’s canonical collection, originally compiled around 1083 and existing in four main recensions: A, B, Bb, and C. Peter Landau suggests that Gratian probably employed a manuscript containing an expanded form of recension A which he calls recension A’;
- the Collectio tripartita attributed to Ivo of Chartres, usually thought to date to 1095;
- the Panormia of Ivo of Chartres, also usually dated to 1095, although several scholars have argued for a later date and some even question Ivo's authorship;
- Gregory of St. Grisogono's Polycarpus, completed some time after 1111;
- the Collection in Three Books, composed some time between 1111 and 1139, though dated by some to around 1123;
- the Glossa ordinaria to the Bible.
Other sources are known to have been used in the composition of particular sections of the Decretum:
- Isidore of Seville's Etymologies for DD. 1-9 (the so-called Treatise on Laws);
- Alger of Liège's Liber de misericordia et iustitia for C. 1;
- the Sententiae magistri A. for the De penitentia and some other sections.
Gratian himself named his work Concordia Discordantium Canonum - "Concord of Discordant Canons." The name is fitting: Gratian tried to harmonize apparently contradictory canons with each other, by discussing different interpretations and deciding on a solution. This dialectical approach allowed for other law professors to work with the Decretum and to develop their own solutions and commentaries.
These commentaries were called glosses. Editions printed in the 15th, 16th or 17th centuries frequently included the glosses along with the text. Collections of glosses were called "gloss apparatus" or Lectura in Decretum (see also glossator). Systematic commentaries were called Summae. Some of these Summae were soon in circulation as well and obtained the same level of fame as the Decretum itself. Early commentators included Paucapalea and Magister Rolandus.
The most important commentators were probably Rufin of Bologna (died before 1192) and Huguccio (died 1210). Less well-known was the commentary of Simon of Bisignano, which consisted of the Glosses on the Decretum and the Summa Simonis.
- Landau, Peter. “Gratians Arbeitsplan.” In Iuri canonico promovendo: Festschrift für Heribert Schmitz zum 65. Geburtstag. Regensburg: F. Pustet, 1994. pp. 691-707.
- Landau, Peter. “Neue Forschungen zu vorgratianischen Kanonessammlungen und den Quellen des gratianischen Dekrets.” Ius Commune 11 (1984): 1-29. Reprinted in idem. Kanones und Dekretalen. pp. 177*-205*
- Landau, Peter. “Quellen und Bedeutung des gratianischen Dekrets,” Studia et Documenta Historiae et Juris 52 (1986): 218-235. Reprinted in idem. Kanones und Dekretalen. pp. 207*-224*.
- Lenherr, Titus. Die Exkommunikations- und Depositionsgewalt der Häretiker bei Gratian und den Dekretisten bis zur Glossa ordinaria des Johannes Teutonicus. St. Ottilien: EOS Verlag, 1987.
- Munier, Charles. Les sources patristiques du droit de l’église du VIIIe au XIIIe siècle. Mulhouse 1957.
- Noonan, John T. "Gratian slept here: the changing identity of the father of the systematic study of canon law." Traditio 35 (1979), 145-172.
- Winroth, Anders. The Making of Gratian’s Decretum. New York: Cambridge University Press, 2000.
- Winroth, Anders. "Recent Work on the Making of Gratian's Decretum," Bulletin of Medieval Canon Law 26 (2008).
- Full Latin text from the Bayerische Staatsbibliothek
- Otto Vervaart's introduction to Canon Law
- Domus Gratiani
- The Stephan Kuttner Institute of Medieval Canon Law in Munich