AUGUSTUS avoided Caesar's mistakes. He grasped at the ./\.substance and let go the shadow of monarchy. His military rule was clothed in republican forms. The Senate conferred on him all the powers of the Republic, and those only for a fixed term of years. These powers were renewed from time to time, not only because he had command of the army, but because with each year the State became more dependent on him. His aims differed from those of Caesar, who had intended to assimilate Italy to the rest of the Empire, for Augustus came from the old Italian stock and wished to ensure its predominance. The Assemblies were permitted to meet and approve legislation and elect candidates recommended by Augustus. The Senate was purged of provincials and freed slaves, and permitted to retain a share in the government. This dyarchy (joint rule) had no basis in fact and the Emperors gradually encroached on the functions of the Senate, and removed the fictions which disguised their military and personal rule. Another influence tending to exalt the Princeps (First Citizen) was the cult of Rome and Augustus. After his death he was deified-a cult taken from the Hellenistic kingdoms-and priests of Augustus were appointed in all cities of the Empire. The infection spread even to Rome, for the giver of peace seemed to be of superhuman power. Augustus preferred to consolidate rather than to extend the Empire. He sought great natural boundaries, such as the Sahara desert, behind the Roman province of Africa, the Euphrates, to mark the division between the Syrian province and the growing empire of the Parthians, and the line of the Rhine and the Danube in the North. This last frontier presented an inconvenient angle at the gap between the two rivers. Augustus tried to straighten it out by advancing to the Elbe, but after the German tribes had wiped out a Roman army in A.D. 9, he fell back again to the Rhine.