领导力意味着做出今天艰难的决定，这些决定将在长远上使公司受益。
Leadership means making tough decisions today that will benefit the company in the long run.
君子勇于改正错误，小人则文过饰非。
用右手画圆形，左手画方形，不能同时画成
Mathematics is not just about numbers, equations, computations, or algorithms: it is about understanding.
The purpose of abstraction is not to be vague, but to create a new semantic level in which one can be absolutely precise.