Under Augustus, Rome lost its republican character, and became an imperial city--a military despotism succeeded to free institutions. Mercenary troops and standing armies took the place of those invincible legions which had been composed of Roman citizens; and the new military power thus created was placed in the hands of the Roman emperor. The senate remained, together with other institutions which had existed in the days of the republic; but they had lost the spirit which had once animated them, and were now overshadowed and rendered almost powerless by the influence of imperial authority. Under Diocletian a system of partition was introduced, when the two Augusti and the two Cæsars became the rulers of the four great provinces into which the Roman empire was divided: this new system affected both the form and the spirit of the government; for, by removing these rulers from the city to their respective provinces, it released them from whatever little restraint the senate might have put upon their proceedings. They became absolute sovereigns, oppressing the provinces by their exactions, and spreading desolation around them, by their wars with each other. Constantine overcame all his rivals in power, and engrossed to himself the whole government of the empire; but by removing his residence and court from Rome to Constantinople, he prepared for that separation of the eastern from the western provinces, which produced in fact two separate and independent empires. Other changes were introduced by Constantine: the despotism of the court succeeded to the despotism of the army: state officers were multiplied without number; and, as Heeren observes, "if the good of a commonwealth consisted in forms, rank and title, the Roman empire must at this time have been truly happy!"[2] How completely had Rome now lost the greatness which she once possessed! patriotism had faded from the empire; the spirit of liberty had expired. If republican forms remained, the life which had once animated them was gone, and they were made the covering for despotic practices, and oriental courtiership. Laws no longer depended on the decrees of the senate, but on the rescripts of emperors, and government sank into a fearful despotism,--the punishment, under Divine Providence, of states unfaithful to liberty. It has been often observed, that despotism was the only kind of rule which could hold the Roman empire together during the last age of its history: but what a striking proof does that fact present of the thoroughly corrupt state of Roman civilisation!