[Modus legendi abbreviaturas]

constitutions are not numbered under the name of a book. But they must be titled "Clementines", as was said above. And the Clementines are divided in the same way into five books, according to the material of this use: "Judge, judgment, clergy, betrothals, crime". Of which those [books], the Decretals and the Sext, treat, although they contain fewer titles, and the titles [contain] fewer chapters, into which they are again divided.

There are, however, examples to be taken in these in such a way. Where it is cited thus: "On heretics", [chapter] "Ad nostrum", in the Clementines, this is abbreviated thus: de her. ad nostrum in Cle., if in the constitutions, the Clementines, under the title "On heretics and Manichaeans", in the chapter which begins "Ad nostrum". Another example: "On relics and the veneration of the saints", [chapter] "Si dominum", in the Cle[mentines]. That is, on relics and the veneration of the saints, in the chapter "Si dominum", in the Clementines, and so on for others. For here it is cited in everything just as in the Decretals, only with this removed, that here "in cle." is added, just as in the Sext "li. vi." is added because of the reason said there. And this addition can be prefixed, so that in citing thus: Cle. pastoralis. §. Rursus in h. (that is, in the Clementines, in the chapter "Pastoralis", in the section "Rursus", in the end of that section where it is said: "He who puts a sickle into another's harvest does his own"). And these should suffice regarding the citations and examples of canon law as far as the four books are concerned. And so that the books may be known:

It should be known that the Decree begins thus: "The human race is governed by two things, namely natural law and custom." The Decretals begin: "Gregory, bishop, servant of the servants of God." The Sext begins: "Boniface, bishop, servant of the servants of God." The Clementines are accustomed to begin in different ways, sometimes thus: "John, bishop, servant of the servants of God. Since no sanction of the law..." Sometimes thus: "Clement, bishop, etc. On the foundation of the Catholic faith, etc." And before I come to the matter of the decree in the distinctions and causes, and to the rubrics in the Decretals, I premise concerning the books of laws and the citations in them.

Concerning the legal books

For the civil or imperial law, which is called the laws, has been handed down to us in many [forms], and generally in four volumes, which are called the legal books. As they are: the Digest, the Code, the Institutes, and the Authentic. To which is added the book of fiefs.

ff

Therefore, the first book of civil law is the Digest, and it contains the laws and statutes of the Romans. And it contains 50 partial books, which are comprised in three volumes. The first volume is the Digestum Vetus (Old Digest), which has 24 partial books. The second, the Inforciatum, and it has 14 partial books. The third,