The essence of its failure was that it could not sustain unity. In its early stages its citizens, both patrician and plebeian, had a certain tradition of justice and good faith, and of the loyalty of all citizens to the law, and of the goodness of the law for all citizens; it clung to this idea of the importance of the law and of law-abidingness nearly into the first century B.C. But the unforeseen invention and development of money, the temptations and disruptions of imperial expansion, the entanglement of electoral methods, weakened and swamped this tradition by presenting old issues in new disguises under which the judgment did not recognize them, and by enabling men to be loyal to the professions of citizenship and disloyal to its spirit. The bond of the Roman people had always been a moral rather than a religious bond; their religion was sacrificial and superstitious; it embodied no such great ideas of a divine leader and of a sacred mission as Judaism was developing. As the idea of citizenship failed and faded before the new occasions, there remained no inner, that is to say no real, unity in the system at all. Every man tended more and more to do what was right in his own eyes.
Under such conditions there was no choice between chaos and a return to monarchy, to the acceptance of some chosen individual as the one unifying will in the state. Of course in that return there is always hidden the expectation that the monarch will become as it were magic, will cease to be merely a petty human being, and will think and feel as something greater and more noble, as indeed a state personage; and of course monarchy invariably fails to satisfy that expectation. We shall glance at the extent of this failure in the brief review we shall presently make of the emperors of Rome. We shall find at last one of the more constructive of these emperors, Constantine the Great, conscious of his own inadequacy as a unifying power, turning to the faith, the organization, and teaching network of one of the new religious movements in the empire, to supply just that permeating and correlating factor in men's minds that was so manifestly wanting.
With Cæsar, the civilization of Europe and Western Asia went back to monarchy, and, through monarchy, assisted presently by organized Christianity, it sought to achieve peace, righteousness, happiness, and world order for close upon eighteen centuries.