过去是幽灵，未来是梦想，我们拥有的只有现在。

To every action there is always opposed an equal reaction； or， the mutual actions of two bodies upon each other are always equal， and directed to contrary parts.

To understand a program you must become both the machine and the program.

数学的美在于它能够用一种超越文化和语言障碍的语言来描述宇宙。