真正的朋友，不是在一起有聊不完的话题，而是在一起，就算不说话，也不会感到尴尬。

在数学中，你不是理解事物，你只是习惯了它们。

The ideas of economists and political philosophers， both when they are right and when they are wrong， are more powerful than is commonly understood. Indeed the world is ruled by little else. Practical men， who believe themselves to be quite exempt from any intellectual influence， are usually the slaves of some defunct economist.