Old minds are like old horses; you must exercise them if you wish to keep them in working order.

The true value of a forest lies in its ability to balance ecological needs with human aspirations.

"We're all just a bunch of guys trying to do something great."

数学家的工作永远不会真正完成；总有更多的东西需要探索。

We think in order to act, and act in order to live.

最好的故事是那些可以一遍又一遍阅读，并带来不断增加的愉悦感的故事。

可持续性不是一种趋势，而是我们对后代的责任。