上句见：Day296
The Story of Philosophy《哲学的故事》第1章Plato第5节V. The Political Problem第4段第1句：

Every form of government tends to perish by excess of its basic principle. Aristocracy ruins itself by limiting too narrowly the circle within which power is confined; oligarchy ruins itself by the incautious scramble for immediate wealth. In either case the end is revolution. When revolution comes it may seem to arise from little causes and petty whims; but though it may spring from slight occasions it is the precipitate result of grave and accumulated wrongs; when a body is weakened by neglected ills, the merest exposure may bring serious disease(556). "Then democracy comes: the poor overcome their opponents, slaughtering some and banishing the rest; an give to the people and equal share of freedom and power"(557).
浙江大学译本：任何政府都会因滥用原则而消亡。

解析

1、Every form of government tends to perish by excess of its basic principle.
任何政体都会因极端化自身原则而消亡。
perish: to disappear or be destroyed: to cease to exist 消亡；丧失
And so long as men die, liberty will never perish.只要人们不畏死亡，自由是永远不会消失的。《名人演讲综合》

这句话概括了政体不稳的原因，既是对上文中贵族被财阀寡头取代的根本原因的解释，又暗示财阀寡头也终走向灭亡。应了那句“成也萧何，败也萧何”。后文中将解释它们各自的原则是什么？