Around computers it is difficult to find the correct unit of time to measure progress. Some cathedrals took a century to complete. Can you imagine the grandeur and scope of a program that would take as long?

动力学的方程在用变分法的语言表达时是完全的。

一个没有森林的世界，就是一个没有呼吸的世界。

The past is a shadow that clings to our heels.

Don't watch the clock; do what it does. Keep going.

为什么一条狗，一匹马，一只耗子都有生命，而你却没有一丝的呼吸。