Their great libraries.  For the establishment and extension of the public libraries, books were sedulously collected.  Thus the khalif Al-Mamun is reported to have brought into Bagdad hundreds of camel-loads of manuscripts.  In a treaty he made with the Greek emperor, Michael iii., he stipulated that one of the Constantinople libraries should be given up to him.  Among the treasures he thus acquired was the treatise of Ptolemy on the mathematical construction of the heavens.  He had it forthwith translated into Arabic, under the title of “Al-magest.”  The collections thus acquired sometimes became very large; thus the Fatimite Library at Cairo contained one hundred thousand volumes, elegantly transcribed and bound.  Among these, there were six thousand five hundred manuscripts on astronomy and medicine alone.  The rules of this library permitted the lending out of books to students resident at Cairo.  It also contained two globes, one of massive silver and one of brass; the latter was said to have been constructed by Ptolemy, the former cost three thousand golden crowns.  The great library of the Spanish khalifs eventually numbered six hundred thousand volumes; its catalogue alone occupied forty-four.  Besides this, there were seventy public libraries in Andalusia.  The collections in the possession of individuals were sometimes very extensive.  A private doctor refused the invitation of a Sultan of Bokhara because the carriage of his books would have required four hundred camels.

There was in every great library a department for the copying or manufacture of translations.  Such manufactures were also often an affair of private enterprise.  Honian, a Nestorian physician, had an establishment of the kind at Bagdad (A.D. 850).  He issued versions of Aristotle, Plato, Hippocrates, Galen, etc.  As to original works, it was the custom of the authorities of colleges to require their professors to prepare treatises on prescribed topics.  Every khalif had his own historian.  Books of romances and tales, such as “The Thousand and One Arabian Nights’ Entertainments,” bear testimony to the creative fancy of the Saracens.  Besides these, there were works on all kinds of subjects—­history, jurisprudence, politics, philosophy, biographies not only of illustrious men, but also of celebrated horses and camels.  These were issued without any censorship or restraint, though, in later times, works on theology required a license for publication.  Books of reference abounded, geographical, statistical, medical, historical dictionaries, and even abridgments or condensations of them, as the “Encyclopedic Dictionary of all the Sciences, by Mohammed Abu Abdallah.  Much pride was taken in the purity and whiteness of the paper, in the skillful intermixture of variously-colored inks, and in the illumination of titles by gilding and other adornments.