doubtful points of the ancient ecclesiastical law by adding some new decretals to ensure his work was clear and concordant. He indicated by the words et infra the passages excised by him in the former collections. They are called partes decisae. The new compilation bore no special title, but was called "Decretales Gregorii IX" or sometimes "Compilatio sexta", i. e. the sixth collection with reference to the "Quinque compilationes antiquæ". It was also called "Collectio seu liber extra", i. e. the collection of the laws not contained (vagantes extra) in the "Decretum" of Gratian. Hence the custom of denoting this collection by the letter X (i.e. extra, here not the Roman numeral for ten). Quotations Quotations from this collection are made by indicating the number of the chapter, the name the work goes by (X), the number of the book, and that of the title. Usually the heading of the title and sometimes the first words of the chapter are quoted; for instance, "c. 3, X, III, 23", or "c. Odoardus, X, De solutionibus, HI, 23", refers to the third chapter, commencing with the word Odoardus, in the Decretals of Gregory IX, book III, title 23, which is entitled "De solutionibus". If the number of the chapter or of the title is not indicated it will easily be learned on consulting the alphabetical indexes of the rubrics and of the introductory words of the chapters, which are to be found in all editions of the "Corpus Juris Canonici". Gregory IX sent this new collection to the Universities of Bologna and Paris, and declared, by the Bull "Rex pacificus" of 5 September 1234, that this compilation was the official code of the canon law. Force of law All its decisions had the force of canon law whether they were authentic or not, whatever the juridical value of the texts considered in themselves, and whatsoever the original text. It is a unique collection; all its decisions were simultaneously promulgated, and are equally obligatory, even if they appear to contain, or if in fact they do contain, antinomies, i. e. contradictions. In this peculiar case it is not possible to overcome the difficulty by recourse to the principle that a law of later date abrogates that of an earlier period. Finally, it is an exclusive collection, i.e. it abrogates all the collections, even the official ones, of a later date than the "Decretum"