He determined to divide the numerous and increasing cares of the distracted empire, so that it might be ruled from two centres--one in the East and the other in the West. In pursuance of this plan, he chose as a colleague a companion soldier, Maximian, upon whom he conferred the title of Augustus. After a few years, finding the cares of the co-sovereignty still too heavy, each sovereign associated with himself an assistant, who took the title of Cæsar, and was considered the son and heir of the emperor. There were thus two Augusti and two Cæsars. Milan, in Italy, became the capital and residence of Maximian; while Nicomedia, in Asia Minor, became the seat of the court of Diocletian. The Augusti took charge of the countries near their respective capitals, while the younger and more active Cæsars were assigned the government of the more distant and turbulent provinces. The vigorous administration of the government in every quarter of the empire was thus secured. The authority of each of the rulers was supreme within the territory allotted him; but all acknowledged Diocletian as "the father and head of the state." [Illustration: DIOCLETIAN.] The most serious drawback to the system of government thus instituted was the heavy expense incident to the maintenance of four courts with their trains of officers and dependants. The taxes became unendurable, husbandry ceased, and large masses of the population were reduced almost to starvation. While the changes made in the government have rendered the name of Diocletian famous in the political history of the Roman state, the cruel persecutions which he ordered against the Christians have made his name in an equal degree infamous in ecclesiastical annals; for it was during this reign that the tenth--the last and severest--of the persecutions of the Church took place. By an imperial decree the churches of the Christians were ordered to be torn down, and they themselves were outlawed. For ten years the fugitives were hunted in forest and cave. The victims were burned, were cast to the wild beasts in the amphitheatre--were put to death by every torture and in every mode that ingenious cruelty could devise. But nothing could shake the constancy of their faith. They courted the death that secured them, as they firmly believed, immediate entrance upon an existence of unending happiness. The exhibition of devotion and constancy shown by the martyrs won multitudes to the persecuted faith. It was during this and the various other persecutions that vexed the Church in the second and third centuries that the Christians sought refuge in the Catacombs, those vast subterranean galleries and chambers under the city of Rome. Here the Christians lived and buried their dead, and on the walls of the chambers sketched rude symbols of their hope and faith. It was in the darkness of these subterranean abodes that Christian art had its beginnings. [Illustration: CHRIST AS THE GOOD SHEPHERD. (From the Catacombs.)]