Gratian

Almost nothing is known for certain about the life of Gratian. Later tradition made him a Camaldolese monk teaching in Bologna, but modern historians doubt this; one theory suggests he became bishop of Chiusi. What is certain is his book. Around 1140 a teacher in Bologna, the city that was then becoming Europe's great centre of legal study, gathered thousands of texts on church law: canons of councils, letters of popes, passages from the Church Fathers and Roman law. Many of these texts contradicted one another. Gratian's work, called the Concordance of Discordant Canons and later known simply as the Decretum, arranged them by topic and showed by argument how the contradictions could be reconciled. It became the standard textbook of canon law in the universities and the first part of the collection later called the Corpus Iuris Canonici, which remained the basic law of the Catholic Church until 1917. Scholars now think the Decretum grew in at least two stages. Gratian probably died before the middle of the twelfth century.

Faith: Faith not well documented beyond his work as a Catholic canon lawyer. Source: Wikipedia

See also: Justinian I · Thomas Aquinas · Stephen Langton