The only service a friend can really render is to keep up your courage by holding up to you a mirror in which you can see a noble image of yourself.
朋友能提供的唯一帮助，就是通过举一面镜子让你看到自己高尚的形象，从而保持勇气。
Agriculture is the foundation of civilization, and we must treat it with the respect it deserves.
一个好的数学家是能看到定理之间类比的人；一个伟大的数学家是能看到类比之间的类比的人。
忠于自己，永远不要让任何人改变你。
数学的美在于它能够将复杂的思想简化为优雅的结构。