History of the Christian Church, Volume IV: Mediaeval Christianity. A.D. 590-1073. by Philip Schaff (Author)General Introduction to Mediaeval Church History. § 1. Sources and Literature. August Potthast: Bibliotheca Historica Medii Aoevi. Wegweiser durch die Geschichtswerke des Europäischen Mittelalters von 375-1500. Berlin, 1862. Supplement, 1868. The mediaeval literature embraces four distinct branches; 1. The Romano-Germanic or Western Christian; 2. The Graeco-Byzantine or Eastern Christian; 3. The Talmudic and Rabbinical; 4. The Arabic and Mohammedan. We notice here only the first and second; the other two will be mentioned in subdivisions as far as they are connected with church history. The Christian literature consists partly of documentary sources, partly of historical works. We confine ourselves here to the most important works of a more general character. Books referring to particular countries and sections of church history will be noticed in the progress of the narrative. I. Documentary Sources. They are mostly in Latin--the official language of the Western Church,--and in Greek,--the official language of the Eastern Church. (1) For the history of missions: the letters and biographies of missionaries. (2) For church polity and government: the official letters of popes, patriarchs, and bishops. The documents of the papal court embrace (a) Regesta (registra), the transactions of the various branches of the papal government from a.d. 1198-1572, deposited in the Vatican library, and difficult of access. (b) Epistolae decretales, which constitute the basis of the Corpus juris canonici, brought to a close in 1313. (c) The bulls (bulla, a seal or stamp of globular form, though some derive it from boulhv, will, decree) and briefs (breve, a short, concise summary), i.e., the official letters since the conclusion of the Canon law. They are of equal authority, but the bulls differ from the briefs by their more solemn form. The bulls are written on parchment, and sealed with a seal of lead or gold, which is stamped on one side with the effigies of Peter and Paul, and on the other with the name of the reigning pope, and attached to the instrument by a string; while the briefs are written on paper, sealed with red wax, and impressed with the seal of the fisherman or Peter in a boat. (3) For the history of Christian life: the biographies of saints, the disciplinary canons of synods, the ascetic literature. (4) For worship and ceremonies: liturgies, hymns, homilies, works of architecture sculpture, painting, poetry, music. The Gothic cathedrals are as striking embodiments of mediaeval Christianity as the Egyptian pyramids are of the civilization of the Pharaohs. (5) For theology and Christian learning: the works of the later fathers (beginning with Gregory I.), schoolmen, mystics, and the forerunners of the Reformation.