正该来时，先生（老子）应时来到这世间；正该去时，先生顺时离开这世间。安于时势，顺应自然规律，哀乐就不能进入心中。

The Langlands conjectures suggest that there is a hidden harmony between different areas of mathematics.

You have to be willing to fail to succeed.

阅读，阅读，再阅读。什么都要读。