The forces of hindrance were political and psychological;[347] and they operated still more powerfully under the Romans than under the successors of Alexander. The dominance of the Greeks over the other races in the eastern provinces did not make them more than a class of privileged tools of Rome; and they deteriorated none the less.[348] When for the stimulating though stormy life of factious self-government there was substituted the iron hand of a conqueror, governing by military force, there was need of a new and intelligent discipline if the mental atmosphere were not to worsen. All civilisation, in so far as it proceeds from and involves a "leisured class," sets up a perpetual risk of new morbid phases. Men must have some normal occupation if their life is to be sound; and where that occupation is not handicraft it can be kept sound and educative only by the perpetual free effort of the intelligence towards new truth, new conception, and new presentment.[349] Nor can this effort conceivably take place on any wide scale, and with any continuity, save in a community kept more or less generally alert by the agitation of vital issues. For a generation or two after Alexander, it is true, there is no arrest in the production of good philosophic minds among the Greeks; indeed, the sudden forcing back of all the best remaining minds on philosophy, as the one mental employment left to self-respecting men of leisure,[350] raised the standards of the study, and led to the ethical systems of Epicurus and Zeno, certainly fit in their way to stand beside those of Plato and Aristotle. So, too, the thrusting back of the drama (which in the hands of Aristophanes had meddled audaciously with every public question) on the study of private life, developed in the highest degree the domestic and psychological bent of the later comedy,[351] very much as the autocracy has developed the novel in contemporary Russia. But the schools of Epicurus and Zeno, both of which outlasted in moral credit and in moral efficacy that of Plato,[352] and the new comedy of Menander, alike represent the as yet unexhausted storage of the mental energy generated by the old political life; and the development is not prolonged in either case. Evidently something vital was lost: only a renewal of the freer life could make possible a continuous advance in intellectual power.