——1963年6月25日在西德市政厅柏林墙前的演说

善是无法定义的。

不成熟状态就是不经别人的引导就无力运用自己的理智。

You can't go back and change the beginning, but you can start where you are and change the ending.

The greatest tragedy is not death, but forgetting one's mother tongue.

The most profound ideas in mathematics often come from asking the simplest questions.

在数学中，没有捷径可走。

Innovation is born at the intersection of curiosity and persistence.

你影响力的唯一限制是你的想象力和承诺。

科技创新没有捷径，必须脚踏实地，久久为功。

The best way to cheer yourself up is to try to cheer somebody else up.