The Pope also gradually established his authority as supreme and sole lawgiver within the Church. The _Dictatus Papae_ asserts that for him alone it is lawful to frame new laws to meet the needs of the time. Meanwhile the Forged Decretals had found their place in the various collections of the Canons made in the eleventh and early twelfth centuries. In the middle of the twelfth century Gratian, a Benedictine monk of Bologna, put out his _Concordantia discordantium Canonum_, commonly known as the _Decretum Gratiani_, which combined a theoretical disquisition with illustrations drawn from the documents which had appeared in previous collections. This became the standard mediaeval treatise in ecclesiastical law, and its appearance much encouraged the systematic study of the Canon law. The Popes of the succeeding century and a half made great additions to the law of the Church, partly through the decrees issued by the General Lateran Councils, partly by their own edicts. Such new matter was embodied from time to time. Thus in 1234 the Dominican Raymund de Pennaforte gathered five books of Decretals at the command of Gregory IX; Boniface VIII was responsible for a sixth book in 1298, while other additions were made by Clement V (1308) and John XXII (1317). All these, together with the earlier compilations and some later additions, formed the _Corpus Juris Canonici_. This enormous body of law was full of contradictions and not devoid of falsification and forgery. The growing study of it caused the foundation of Chairs at the universities, and the Popes found it a most convenient method to publish their new decrees through the lecture-rooms. The old Canon Law was entirely superseded by the later Papal Law. [Sidenote: Power over Councils.]