About the end of the century appeared a new code from the pen of Ivo, Bishop of Chartres, whose acquaintance with the civil law of Rome enabled him to give to his work a superiority over the compilations of his predecessors. Yet the knowledge of Ivo must have been confined to the Theodosian code, the institutes and mutilated extracts from the pandects of Justinian. But when Amalphi was taken by the Pisans in 1137, an entire copy of the last work was discovered; and its publication immediately attracted, and almost monopolized, the attention of the learned. Among the students and admirers of the pandects was Gratian, a monk of Bologna, who conceived the idea of compiling a digest of the canon law on the model of that favorite work; and soon afterwards, having incorporated with his own labors the collections of former writers, he gave his "decretum" to the public in 1151. From that moment the two codes, the civil and canon laws, were deemed the principal repositories of legal knowledge; and the study of each was supposed necessary to throw light on the other. Roger, the bachelor, a monk of Bec, had already read lectures on the sister sciences in England, but he was advanced to the government of his abbey; and the English scholars, immediately after the publication of the decretum, crowded to the more renowned professors in the city of Bologna. After their return they practised in the episcopal courts; their respective merits were easily appreciated, and the proficiency of the more eminent was rewarded with an ample harvest of wealth and preferment.