The definition of a good mathematical problem is the mathematics it generates rather than the problem itself.
The only real sin is regret.
The art of medicine consists in amusing the patient while nature cures the disease.
别让恐惧决定你的未来。
世界上有一条唯一的路,除你之外无人能走。它通往何方?不要问,走便是了。
This is how the entire course of a life can be changed: by doing nothing.