做你自己，别人都已经有人做了。

沾沾自喜时，应该约束反省；怒不可遏时，应该约束反省；怠倦懒惰时，应该约束反省；思想狂放时，应该省约束反。

The first fruit of this imagination - and the first lesson of the social science that embodies it - is the idea that the individual can understand his own experience and gauge his own fate only by locating himself within his period, that he can know his own chances in life only by becoming aware of those of all individuals in his circumstances.

写作不是为了交流，而是为了思考。

数学研究是所有自然现象精确知识不可或缺的基础。