The powers which Augustus held were granted to him for life or for a term of years. It was not easy to arrange for their transmission to a successor, but he cleverly surmounted the difficulty by naming Tiberius as heir to his private fortune and by having him invested with the _imperium_ and with the tribunician power. The theory of the republican magistracy was kept intact, inasmuch as the two powers just mentioned were conferred on Tiberius by the senate in coöperation with the people, but the action of the popular assembly was a pure matter of form, and the senate could be counted on to approve the choice of the prince. The precedent which Augustus set was followed by his immediate successors. He materially strengthened his position by clearly marking off certain social classes from the rest of the population and by making their privileges dependent on his favor. No one could become a senator unless he had been elected to a magistracy, and success in an election required the support of the prince. He gave dignity to the knighthood and definiteness to its membership by making important appointments from its ranks, and by revising the list of knights at regular intervals. He even created an aristocracy among the freedmen in the municipalities. No survey of Roman politics would be complete without some account of political life in these municipalities, for, as we have already noticed, the city was the organic political unit in antiquity. Several municipal charters,[9] most of which have been found within the last fifty or seventy-five years, give us a clear idea of the municipal system in the West and of the efforts which were made in the early empire to improve it and make it uniform. In cities of the typical form there were two local chief magistrates corresponding to the early republican consuls, two minor magistrates who bore the title of aediles, a senate or common council of one hundred members, and a popular assembly. The system adopted was conservative, inasmuch as the control of local affairs rested largely with the local senate, and the magistrates were its ministers. Most cities were allowed to keep a large measure of self-government under the early empire, and this fact kept alive the sentiment of local pride and the local patriotism of the citizens. So long as the cities were free to manage their own affairs, the empire was prosperous. As the cities lost their sense of responsibility, or as the central government encroached on their rights, as it began to do in the second century of our era, the decline of the empire set in. It was to this halcyon period of municipal prosperity from the latter part of the first to the close of the second century that Gibbon pays his famous tribute in the third chapter of his history: “If a man were called to fix the period in the history of the world, during which the condition of the human race was most happy and prosperous, he would, without hesitation, name that which elapsed from