书籍是最安静、最恒久的朋友；它们是最易接近、最睿智的顾问，也是最耐心的老师。
The human being is always more than what he knows of himself.
人类的状况是不断的斗争，但也是无尽的可能性。
In mathematics, you don't understand things. You just get used to them.
我们德国人永远不会摆脱希特勒。他就像我们脸上的胎记。