交换、交易和互换的倾向普遍存在于所有人之中,而在其他动物种族中找不到。
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.
The true value of a forest cannot be measured in board feet alone.
成为你希望在世界上看到的改变。