On the other hand, this simple harmony had very serious limitations, which in the end involved the downfall of the city system. The responsibilities and privileges of the associated life were based not on the rights of human personality but on the rights of citizenship, and citizenship was never coextensive with the community. The population included slaves or serfs, and in many cities there were large classes descended from the original conquered population, personally free but excluded from the governing circle. Notwithstanding the relative simplicity of social conditions the city was constantly torn by the disputes of faction—in part probably a legacy from the old clan organization, in part a consequence of the growth of wealth and the newer distinction of classes. The evil of faction was aggravated by the ill-success of the city organization in dealing with the problem of interstate relations. The Greek city clung to its autonomy, and though the principle of federalism which might have solved the problem was ultimately brought into play, it came too late in Greek history to save the nation.
The constructive genius of Rome devised a different method of dealing with the political problems involved in expanding relations. Roman citizenship was extended till it included all Italy and, later on, till it comprised the whole free population of the Mediterranean basin. But this extension was even more fatal to the free self-government of a city state. The population of Italy could not meet in the Forum of Rome or the Plain of Mars to elect consuls and pass laws, and the more wisely it was extended the less valuable for any political purpose did citizenship become. The history of Rome, in fact, might be taken as a vast illustration of the difficulty of building up an extended empire on any basis but that of personal despotism resting on military force and maintaining peace and order through the efficiency of the bureaucratic machine. In this vast mechanism it was the army that was the seat of power, or rather it was each army at its post on some distant frontier that was a potential seat of power. The “secret of the empire” that was early divulged was that an emperor could be made elsewhere than at Rome, and though a certain sanctity remained to the person of the emperor, and legists cherished a dim remembrance of the theory that he embodied the popular will, the fact was that he was the choice of a powerful army, ratified by the God of Battles, and maintaining his power as long as he could suppress any rival pretender. The breakup of the Empire through the continual repetition of military strife was accelerated, not caused, by the presence of barbarism both within and without the frontiers. To restore the elements of order a compromise between central and local jurisdictions was necessary, and the vassal became a local prince owning an allegiance, more or less real as the case might be, to a distant sovereign. Meanwhile, with the prevailing disorder the mass of the population in Western Europe lost its freedom, partly through conquest, partly through the necessity of finding a protector in troublous times. The social structure of the Middle Ages accordingly assumed the hierarchical form which we speak of as the Feudal system. In this thoroughgoing application of the principle of authority every man, in theory, had his master. The serf held of his lord, who held of a great seigneur, who held of the king. The king in the completer theory held of the emperor who was