not participants. Science and art were neglected, and in literature they were largely indebted to the Greeks. Only in building and public works did the practical spirit of the Romans assert itself with any originality. Even here outside assistance was relied upon to furnish the necessary technical skill, the order issued by Augustus Cæsar that all the world should be taxed being based on a survey by Egyptian surveyors.
The fifth century A.D. was known as the "Era of the Great Migration." Owing, it is supposed, to climatic changes, the Teutonic tribes inhabiting the great central plain of Europe were forced outward, and poured east and south into the Roman empire. So great was the disturbance occasioned by this outbreak that nearly two centuries elapsed before the turbulance subsided sufficiently to note the changes that had taken place. Meanwhile an invasion from the east threatened for a time to give an Asiatic cast to civilization. With the fanaticism bred by the inaccessible deserts of the Arabian peninsula, the Saracens in the seventh century swept westward until they reached southern France, where the tide was finally turned by Charles Martel on the field of Tours. No less astonishing than their conquests was the facility with which the Arabs assimilated the culture and learning of the nations whom they subjugated. Their capitol Bagdad, situated on the Euphrates midway between Greece and India, soon became by reason of its location the meeting place for the scientific thought of these nations, whence it was transmitted by their conquests to western Europe. The mathematical attainment of the Arabs was, however, distinct from those of either Greece or India, its trend being determined by their religious observances. Thus the extent of the Moslem dominions coupled with the requirement that a believer should face toward Mecca during prayer, made a determination of direction necessary. Also the performance of prayers and ablutions at definite hours of the day and night required an accurate determination of time, while the motion of the moon had to be observed in order to fix the dates of their feasts. From these and similar reasons the Arabs became active in astronomical research, and in consequence developed the auxiliary science of trigonometry.
The turmoil attendant upon the invasion of the ancient world by the Teutons and Saracens so obscured the progress of civilization that this period, although in reality one of beginnings, is known in history as the Dark Ages. The most important feature of this vast influx of barbarians, so-called, was the rapid conversion of the Teutons to Christianity. A colder climate had bred in them a more vigorous mentality and a higher type of morality than that of the south, and Christianity appealed with especial force to their innate love of freedom and spirit of brotherhood. History thus far had been a record of the physical
