Thucydides, History of the Peloponnesian War
Benjamin Jowett, Ed.

19. 'The Lacedaemonians invite you to make terms with them and to finish the war. They offer¹ peace and alliance and a general friendly and happy relation, and they ask in return their countrymen who are cut off in the island. They think it better that neither city should run any further risk, you of the escape of the besieged, who may find some means of forcing their way out, we of their being compelled to surrender and passing absolutely into your hands. [2] We think that great enmities are most effectually reconciled, not when one party seeks revenge and, getting a decided superiority, binds his adversary by enforced oaths and makes a treaty with him on unequal terms, but when, having it in his power to do all this, he from a generous and equitable feeling overcomes his resentment, and by the moderation of his terms surprises his adversary, [3] who, having suffered no violence at his hands, is bound to recompense his generosity not with evil but with good, and who therefore, from a sense of honour, is more likely to keep his word. [4] And mankind are more ready to make such a concession to their greater enemies than to those with whom they have only a slight difference². Again, they joyfully give way to those who first give way themselves, although against overbearing power they will risk a conflict even contrary to their own better judgment.