The propensity to truck， barter， and exchange one thing for another is common to all men， and to be found in no other race of animals.

生活是世界上最稀有的事情。大多数人只是存在，仅此而已。

Our approach is to observe carefully before acting.

最激动人心的发现往往来自于以全新的方式看待老问题。