This gave clearness to the whole, as before its discovery the study of Roman law was like the study of Aristotle when only parts of the _Organon_ were known. Irnerius and his co-laborers at Bologna now collected and arranged the entire body of Roman civil law (_Corpus Juris Civilis_) (R. 93), introduced the _Digest_ to western Europe, and thus made a new contribution of first importance to the list of possible higher studies. Law now ceased to be a part of Rhetoric (p. 157) and became a new subject of study, with a body of material large enough to occupy a student for several years. This was an event of great intellectual significance. A new study was now evolved which offered great possibilities for intellectual activity and the exercise of the critical faculty, while at the same time showing veneration for authority. Law was thus placed alongside Theology as a professional subject, and the evolution of the professional lawyer from the priest was now for the first time made possible. CANON LAW ALSO ORGANIZED AS A SUBJECT OF STUDY. Inspired by the revival of the study of civil law, a monk of Bologna, Gratian by name, set himself to make a compilation of all the Church canons which had been enacted since the Council of Nicaea (325) formulated the first twenty (p. 96), and of the rules for church government as laid down by the church authorities. This he issued in textbook form, about 1142, under the title of _Decretum Gratiani_. So successful were his efforts that his compilation was "one of those great textbooks that take the world by storm." It did for canon (church) law what the rediscovery of the Justinian _Code_ had done for civil law; that is, it organized canon law as a new and important teaching subject. The _Decretum_ of Gratian was published in three parts, and was organized after the same plan as Abelard's _Sic et Non_, except that Gratian drew conclusions from the mass of evidence he presented on each topic. It contained 147 "Distinctions" (questions; cases of church policy), upon each of which were cited the church canons and the views and decisions of important church authorities. [18] This volume was added to by popes later on, [19] so that by the fifteenth century a large body of canon law had grown up, which was known as the _Corpus Juris Canonici_. Canon Law was thus separated from Theology and added to Civil Law as another new subject of study for both theological and legal students, and the two subjects of Canon and Civil Law came to constitute the work of the law faculties in the universities which soon arose in western Europe. [Illustration: FIG. 56. THE FATHER OF MEDICINE HIPPOCRATES OF COS (460- 367? B.C.)]