"In observational studies, we often have to rely on assumptions that are not directly testable."

History is the present. That's why every generation writes it anew. But what most people think of as history is its end product, myth.

The most important skill in mathematics is the ability to ask the right questions.

到了我这个年纪的时候就会发现，衡量自己成功的标准就是有多少人在真正关心你、爱你。

唯一真正属于你的是你的态度。

衡量一个领导者的真正标准是他们在充满挑战的时期如何应对。