Paul of Ægina also belongs to the class of compilers; but in utilizing the writings of the great physicians who had preceded him, he gives evidence of exquisite good sense, and not infrequently subjects the assertions of his predecessors to an intelligent and enlightened criticism. Besides, he inserts here and there observations and experiences of his own that are not without interest. He has always been, and rightly so, considered one of the greatest physicians of ancient times, the great reputation which he justly held among the Arabs contributing not a little to his renown. This author is the last of the Byzantine period, and with him, therefore, we must close the earlier part of the history of dentistry. If, before passing to the middle period, we cast a glance over the ground already traversed, it is easy to perceive that dental art, in ancient times, reached its highest degree of development at the time when the Roman civilization was in its greatest splendor, when, in the capital of the world, wealth, luxury, and the refinements of social life marvellously increased its needs, and by this also gave an impulse to the evolution of all human activity. But ancient civilization, after having reached its culminating point, soon fell into decadence, and this necessarily would result in a hindrance to the development of dental art. From the days of Archigenes right up to those of Paul of Ægina, dentistry did not make the least progress; indeed, as far as prosthetic dentistry is concerned, there was probably a retrograde movement, it being very likely that when Italy was subject to the dominion of the barbarians and when Christianity—which but recently had asserted itself—was strongly imposing on the human mind a deep contempt for all that regarded the welfare and beauty of the human body, no one could, any longer, think of artificially repairing the losses sustained by the dental system through disease or injury. PART II. SECOND PERIOD—THE MIDDLE AGES. CHAPTER VIII. THE ARABIANS. The religious fanaticism excited by Islamism, transformed the obscure and nomad inhabitants of Arabia into a conquering nation, who very soon extended their power over a considerable part of Asia, Africa, and Europe. Spain, invaded by the Arabs in 711, fell almost entirely into their hands. After having by force of arms rendered themselves powerful and dreaded, the Arabians acquired also great fame by the culture of art and science within the limits allowed them by their religious code; and in these, for more than four centuries, they maintained an incontestable preëminence.