The function of a system of hypotheses is to warn us beforehand what will be our experience—to enable us to make accurate predictions.
办丧事虽有一定的礼仪,但还是以哀痛为本。 
不了解一个国家的文学,就无法理解这个国家的历史。
The most important thing in mathematics is to have a good intuition.
在每一本书中,都有作者灵魂的一部分。
The only real prison is the one you build for yourself.