Of the great schoolmen we still have many works left to us which are very lengthy, so that it is no easy task to study them: the later they are, the more formal do they become. The Schoolmen did not only write compendiums—for the writings of Duns Scotus amount to twelve, and those of Thomas Aquinas to eighteen folios. Abstracts of them are to be found in various works. The principal sources from which we obtain our knowledge are: 1, Lambertus Danæus in the Prolegomena to his _Commentarius in librum primum sententiarum Petri Lombardi, Genevæ_, 1580. (This is the best authority we have in abridged form); 2, Launoi: _De varia Aristotelis in Academia Parisiensi fortuna_; 3, Cramer: Continuation of Bossuet’s History of the World, in the last two volumes; 4, the _Summa_ of Thomas Aquinas. In Tiedemann’s History of Philosophy extracts from the Scholastics are also to be found, as likewise in Tennemann; Rixner also makes judicious extracts. We shall limit ourselves to general points of view. The name finds its origin in this way. From the time of Charles the Great it was only in two places—in the great schools attached to the great cathedral churches and monasteries—that a cleric, that is a canon who had the oversight of the instructors (_informatores_), was called _scholasticus_; he likewise gave lectures on the most important branch of science, theology. In the monasteries he who was the most advanced instructed the monks. We have not, properly speaking, to deal with these; but although scholastic philosophy was something altogether different, the name of Scholastics attached itself to those alone who propounded their theology scientifically and in a system. In place of the _patres ecclesiæ_ there thus arose later on the _doctores_.