History of the Peloponnesian War
Thucydides
Thucydides, Vol. 1-4. Smith, Charles Foster, translator. London and Cambridge, MA: Heinemann and Harvard University Press, 1919-1923.
At this crisis, when the life of the city had been thrown into utter confusion, human nature, now triumphant over the laws, and accustomed even in spite of the laws to do wrong, took delight in showing that its passions were ungovernable, that it was stronger than justice and an enemy to all superiority. For surely no man would have put revenge before religion, and gain before innocence of wrong, had not envy swayed him with her blighting power.
Indeed, men do not hesitate, when they seek to avenge themselves upon others, to abrogate in advance the common principles observed in such cases—those principles upon which depends every man's own hope of salvation should he himself be overtaken by misfortune—thus failing to leave them in force against the time when perchance a man in peril shall have need of some one of them.
Such then were the first outbreaks of passion which the Corcyraeans who remained at home indulged in toward each other; and Eurymedon sailed away with the Athenian fleet.
Later, however, the Corcyraean fugitives, of whom about five hundred[*](cf. 3.20.2.) had got safely across to the mainland, seized some forts there, and thus dominating the territory belonging to Corcyra on the opposite coast made it a base from which they plundered the people of the island and did them much harm, so that a severe famine arose in the city.
They also sent envoys to Lacedaemon and Corinth to negotiate for their restoration; but since nothing was accomplished by these they afterwards procured boats and mercenaries and crossed over to the island, about six hundred in all. They then burned their boats, in order that they might despair of success unless they dominated the country, and went up to Mt. Istone, and after building a fort there began to destroy the people in the city, exercising dominion over the country.