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

When troubles had once begun in the cities, those who followed carried the revolutionary⁴ spirit further and further, and determined to outdo the report of all who had preceded them by the ingenuity of their enterprises and the atrocity of their revenges. [3] The meaning of words had no longer the same relation to things, but was changed by them as they thought proper. Reckless daring was held to be loyal courage; prudent delay was the excuse of a coward; moderation was the disguise of unmanly weakness; [4] to know everything was to do nothing. Frantic energy was the true quality of a man. A conspirator who wanted to be safe was a recreant in disguise. The lover of violence was always trusted, and his opponent suspected. He who succeeded in a plot was deemed knowing, but a still greater master in craft was he who detected one. [5] On the other hand, he who plotted from the first to have nothing to do with plots was a breaker up of parties and a poltroon who was afraid of the enemy. In a word, he who could outstrip another in a bad action was applauded, and so was he who encouraged to evil one who had no idea of it. The tie of party was stronger than the tie of blood, because a partisan was more ready to dare without asking why. [6] (For party associations are not based upon any established law, nor do they seek the public good; they are formed in defiance of the laws and from self-interest.) The seal of good faith was not divine law, but fellowship in crime. If an enemy when he was in the ascendant offered fair words, the opposite party received them not in a generous spirit⁵, but by a jealous watchfulness of his actions⁶. [7] Revenge was dearer than self-preservation. Any agreements sworn to by either party, when they could do nothing else, were binding as long as both were powerless. But he who on a favourable opportunity first took courage, and struck at his enemy when he saw him off his guard, had greater pleasure in a perfidious than he would have had in an open act of revenge; he congratulated himself that he had taken the safer course, and also that he had overreached his enemy and gained the prize of superior ability. In general the dishonest more easily gain credit for cleverness than the simple for goodness; men take a pride in the one, but are ashamed of the other.

The cause of all these evils was the love of power, originating in avarice and ambition,⁷ and the party-spirit which is engendered by them when men are fairly embarked in a contest. [8] For the leaders on either side used specious names, the one party professing to uphold the constitutional equality of the many, the other the wisdom of an aristocracy, while they made the public interests, to which in name they were devoted, in reality their prize. Striving in every way to overcome each other, they committed the most monstrous crimes; yet even these were surpassed by the magnitude of their revenges which they pursued to the very utmost⁸, neither party observing any definite limits either of justice or public expediency, but both alike making the caprice of the moment their law. Either by the help of an unrighteous sentence, or grasping power with the strong hand, they were eager to satiate the impatience of party-spirit. Neither faction cared for religion; but any fair pretence which succeeded in effecting some odious purpose was greatly lauded. And the citizens who were of neither party fell a prey to both; either they were disliked because they held aloof, or men were jealous of their surviving.