I went to the woods because I wanted to live deliberately. I wanted to live deep and suck out all the marrow of life. To put to rout all that was not life. And not, when I had come to die, discover that I had not lived.

在数学中，提出问题的艺术必须比解决问题更有价值。

暴力是无能者的最后避难所。

可持续发展已不再是一种选择，而是我们对后代的责任。