书籍是理解世界和我们自己的钥匙。

The great secret that all old people share is that you really haven't changed in seventy or eighty years. Your body changes, but you don't change at all. And that, of course, causes great confusion.

不要担心你在数学上遇到的困难；我敢保证我遇到的困难比你还大得多。

这一刻全力以赴，下一刻成就最佳。