Rediscovered ca. 1075 and taught in Bologna
Mosaic of Emperor Justinian
San Vitale, Ravenna
Saint Omer, Bibliothèque muncipale 453, fol. 10r
Concordia discordantium canonum = Decretum
Gratian of Clusio ca. †1140
Decretum
The First Collection of Canon Law that was used in all the law schools of Europe.