In his general relations with the subject populations and vassal kingdoms, the Persian seems to have followed a policy of forbearance and liberality which is extraordinary at that period. The language, customs, religion, and local laws of the various peoples were respected; even their rulers were in many cases allowed to remain in power, provided always that their rule was in conformity with Persian interests. The Greek cities of Asia are an instance in point. They were allowed to retain such local self-government as they had possessed under their Lydian suzerain, with the exception that, for any democracies which had existed in them, either an aristocracy, or a Greek tyrant ruling in the Persian interest, was substituted. Such was the case, at any rate, before the Ionian revolt Motives of self-interest obviously contributed to this policy. The maintenance of local institutions in the empire, and the avoidance of complete unification, were eminently calculated to keep the various populations separate, and to prevent the spread of any rebellion over a wide area. To use a modern simile, the provinces were converted, in so far as possible, into compartments fireproof against the flame of insurrection. There can be no question that, throughout the vast area of the empire as a whole, the condition of the population generally was greatly ameliorated in comparison with its life in the past. Precautions were taken to safeguard the subject from oppression by high officials. Apart from the check which the triple division of direct responsibility placed on the arbitrary exercise of power, a special body of officers, known to the Greeks as the king’s “eyes” or “ears,” went on annual circuits through the empire, and reported any case of abuse in the administration. The intention, at any rate, was good; though it may be doubted whether the system could guarantee the provincial from acts of oppression on the part of officials who had a mind to act in arbitrary fashion.