一本好书是最好的朋友，今天如此，永远如此。
Every life is in many days, day after day. We walk through ourselves, meeting robbers, ghosts, giants, old men, young men, wives, widows, brothers-in-love, but always meeting ourselves.
The most profound discoveries in mathematics often come from questioning the most basic assumptions.
数学中最深刻的发现往往来自于对最基本假设的质疑。