century saw a great production of handbooks and compendia—what every man ought to know about theology or law in short and readable form. Many of these books were written in the vernacular; they ranged from encyclopedias, such as the Livre dou Tresor of Brunetto Latini, to brief treatises on ethics and the articles of the faith. Important historical works were also written in the vernacular, especially on the subject of the Crusades. The first great monument of French prose is Villehardouin's account of the conquest of Constantinople; even more famous is Joinville's life of St. Louis, which is largely a description of the Sixth Crusade. As these examples show, French was still the dominant vernacular language; it was understood by nobles and townsmen of all European countries. And the fact that prose masterpieces could be written in French shows that the language had come of age, for it is much harder to write good prose than good verse in the early period of any language.
It was still true, however, that most serious writing was in Latin. Here again, the audience was wider; there were many laymen who could understand the relatively simple and straightforward Latin of the thirteenth century. Treatises on the proper management of great estates or digests of customary law were not written primarily for churchmen. University students, though technically members of the clergy, often had a very secular point of view, and many books were written by and for them. In fact, the scholarly work of the thirteenth century cannot be separated into the categories of secular and ecclesiastical learning; it influenced all educated men.
Logic, order, and reason dominate the learning of the thirteenth century just as they dominate other activities. Each branch of knowledge is arranged in a complete and orderly synthesis; nothing is left out; no contradictions are permitted to remain. The tendency toward encyclopedism, which we have already noted in vernacular literature, was even stronger in Latin treatises. For example, every important legal system was summarized in an
