有用是这些老人曾经对自己最好的希望，而无目的是他们最深的恐惧。
"To be useful was the best thing the old men ever hoped for themselves, and to be aimless was their worst fear."
文字有治愈和毁灭的力量。
不登上高山，就不知道天是多么高远；不亲临深溪，就不知道地是多么深厚。
There are two ways to write error-free programs; only the third one works.
Don't watch the clock; do what it does. Keep going.