Even the philosophers regarded a state of war as the normal and natural relation of Hellenes and barbarians. Aristotle, as we have seen, taught that barbarians might, without moral scruple, be hunted like wild animals.[493] Plato had no word of condemnation of war by Greek against non-Greek. But the Greeks had an uneasy feeling respecting the rightfulness of war between Greek and Greek; and there came a time when the best-instructed conscience of Greece positively denounced wars of this kind. Plato condemned wars between Hellenes and Hellenes as unnatural.[494] This feeling had a kind of restraining influence upon the Greek cities, and there are many instances of arbitration in Greek history. Sometimes a single person of eminence acted as mediator; but oftener some city or league like the Delphian Amphictyony was chosen as the arbitrator. In the Hellenistic Age the Roman Senate frequently undertook the commission of arbitrating quarrels. The cities concerned were sometimes bound by oath or by a deposit of money to abide by the decision. Oftener, however, the decisions rendered, like those by the Hague Tribunal of to-day, depended for their execution upon the good will and honor of the states concerned. There are instances recorded where one or both of the parties refused to abide by the judgment of the arbitrator.[495] Various motives, it is true, were at work in these arbitration treaties, but the ethical motive was certainly operative to a greater or less degree. There was not lacking the feeling, vague though it may have been, which was later given explicit expression by Plato, that war between Greek and Greek was wrong and a crime against Hellenic civilization. But the most interesting and instructive of all the measures taken by the Greeks to limit wars among themselves or to fence them away from a given district was the consecration, by common consent and agreement, of the land of Elis--wherein was situated the sacred Olympia--to perpetual peace and the establishment of a truce of forty days, embracing the festival period of the Olympian games, during which it was sacrilegious for one Greek city to make war upon another. With true vision the philosopher-historian Laurent sees in the little land of Elis, inviolable as a temple, a prophecy of the time when the whole earth shall be consecrated to perpetual peace--an ideal toward which humanity unceasingly advances.[496] [Sidenote: Socrates and his relation to the moral movement]