对于非礼的事，上等到的士人根本不想；对于非礼的事，中等的士人从来不说；对于非礼的事，下等的士人紧闭门户。

长期来看，风险与回报是相关的。但在短期内，这种关系常常是反常的。

The challenge in theoretical computer science is not just to solve problems, but to understand the nature of problem-solving itself.

We are at a unique stage in our history. Never before have we had such an awareness of what we are doing to the planet, and never before have we had the power to do something about it.

世界是一本书，不旅行的人只读了一页。