Another cause was the excessive concentra tion of the people into cities, where the lack of sanitary arrangements, such as now exist, brought about • an enormous where too the relatively high standard of living and the want of remunerative occupations discour aged the rearing of families. Hence the city population had continually to be recruited from the country; and when the rural districts came to be sparsely inhabited, the consequent disap pearance of the cities was accompanied by the wreck of ancient civilization. Among the con tributory causes was slavery, which long before Marcus Aurelius had been destroying the free population; in his time the plague, and after him foreign and civil wars, continued to waste life, while the burden of taxation, always in creasing, made life every day more wretched. The wealth of the empire flowed to the East in exchange for useless luxuries; and for want of gold and silver the coinage was debased; at the same time the cost of living became exces sive. Then, too, the growing splendor of the imperial courts added to the burden. With their scant means many found it impossible to support families, and even the slaves grew fewer. In these conditions most of the lower population, free and slave, became hereditary serfs — colani — bound to the soil and to the payment of fixed dues to their lords. But it was not only the poor who suffered. The municipalities had once enjoyed freedom in local affairs, each governed by a senate, whose members — decuriones — were the wealthier men of the community. Gradually the emper ors encroached upon the liberty of these cities, till they had converted even the privileges of the senators into intolerable burdens. For as these officials were responsible for the taxes due from their districts, many of them, unable to wring the required amount from the poorer classes, were themselves reduced to poverty. Nevertheless they could in no way shirk their duty, but were held for life by an iron hand to the unenviable task of collecting and of pay ing oppressive taxes. Artisans and traders, too, were bound strictly to their hereditary vo cations, in order that the government might be sure of the dues to which they were subject.. In brief, society was forced into a rigid caste like system, which crushed freedom and made the life of rich and poor, bond and free, almost equally wretched. Under these circumstances, and after ages of governmental brow-beating, the inhabitants of the empire lost their interest in the welfare of the state, of the community, of future generations. As the civilized part of the human race lost love of life and hope for the future, it began rapidly to die out, and those who still lived grew continually more barba rous. As they were unwarlike, the government found it more and more necessary to make up the armies of Germans, who consequently set tled in the empire in ever-increasing numbers.
Although they readily adopted Roman civiliza tion, their independent spirit, out of harmony with the conditions above described, acted as a new distintegrating force. Another power, which while aiming to make the world over on its own model tended to destroy ancient ideas and institutions,— including the empire itself,— was Christianity. Rome, essentially polytheis tic, always tolerated the religions of the nations which she conquered; in the adoption of their gods into her pantheon she found a means of political centralization. Judaism, however, she regarded with disfavor, and attempted to sup press Christianity. These exceptions to her policy of toleration were due to the irreconcil able conflict between monotheism and polythe ism and to the leveling tendency of the Chris tian religion. The apostles of Christ taught that the gods of Rome were demons, that the worship of the emperor was sinful, that all men from the emperor to the slave were equal be fore God, that the heaping up of wealth was an abomination; in brief their religion seemed to the Romans subversive of all the principles on which the empire rested. But • although Christianity and Germanism were disintegrat ing the empire, they were destined in combina tion to make the old world new. The estimate of their value as creative agencies belongs to the medizeval period.
In appearance more formidable than internal decay were the hostile nations outside the em pire. In the 3d century the Germans, who had long been threatening, began to break through the northern frontier. The Franks flung them selves upon Gaul; the Goths occupied Dacia and crossed the Danube to defeat and kill an em peror. In the East, too, a new danger ap peared; on the ruins of the old Seleucid power had arisen in the Parthian Empire, which in the 3d century was supplanted by a new, vigorous Persian Empire. The warlike Persian monarchs nearly made good their threat to drive the Romans from Asia.
Early in the 5rh century the Germans began to establish their states within the empire—the Visigothic kingdom in Gaul and Spain (415 A.D.), that of the Vandals in Africa and of the Burgundians in the Rhone Valley. About the middle of the century the Angles and Saxons began to overrun Britain; a little later the Franks, who long before had crossed the Rhine, began the conquest of Gaul (486 A.D.) ; and in 493 A.D. the Ostrogoths conquered Italy. Before the end of the century the western branch of the empire had fallen into the hands of Ger manic chiefs, who while vaguely recognizing the emperor at Constantinople as their lord were in reality sovereign kings of the countries they ruled. Here ancient history ends.