[Footnote 3: The volume of literature which bears more or less on economic matters dating from the fourteenth and fifteenth centuries is colossal. By far the best account of it is to be found in Endemann's _Studien in der Romanisch-canonistischen Wirthschafts- und Rechtslehre_, vol. i. pp. 25 _et seq_. Many of the more important works written during the period are reprinted in the _Tractatus Universi Juris_, vols. vi. and vii. The appendix to the first chapter of Reseller's _Geschichte_ also contains a valuable account of certain typical writers, especially of Langenstein and Henricus de Hoyta. Brants gives a useful bibliographical list of both mediæval and modern authorities in the second chapter of his _Théories économiques aux xiii^{e} et xiv^{e} siècles_. Those who desire further information about any particular writer of the period will find it in Stintzing, _Literaturgeschichte des röm. Rechts_, or in Chevallier's _Répertoire historique des Sources du moyen âge; Bio-bibliographie_. The authorship of the treatise _De Regimine Principum_, from which we shall frequently quote, often attributed to Aquinas, is very doubtful. The most probable opinion is that the first book and the first three chapters of the second are by Aquinas, and the remainder by another writer. (See Franck, _Réformateurs et Publicistes_, vol. i. p. 83.)] § 3. _Teaching_. We shall confine our attention in this essay to the economic teaching of the Middle Ages, and shall not deal with the actual practice of the period. It may be objected that a study of the former without a study of the latter is futile and useless; that the economic teaching of a period can only be satisfactorily learnt from a study of its actual economic institutions and customs; and that the scholastic teaching was nothing but a casuistical attempt to reconcile the early Christian dogmas with the ever-widening exigencies of real life. Endemann, for instance, devotes a great part of his invaluable books on the subject to demonstrating how impracticable the canonist teaching was when it was applied to real life, and recounting the casuistical devices that were resorted to in order to reconcile the teaching of the Church with the accepted mercantile customs of the time. Endemann, however, in spite of his colossal research and unrivalled acquaintance with original authorities, was essentially hostile to the system which he undertook to explain, and thus lacked the most essential quality of a satisfactory expositor, namely, sympathy with his subject. He does not appear to have realised that development and adaptability to new situations, far from being marks of impracticability, are rather the signs of vitality and of elasticity. This is not the place to discuss how far the doctrine of the late fifteenth differed from that of the early thirteenth century; that is a matter which will appear below when each of the leading principles of scholastic economic teaching