It is not from the benevolence of the butcher， the brewer， or the baker that we expect our dinner， but from their regard to their own interest.

The soul needs only one thing: to do what the body is doing.

Our greatest natural resource is the minds of our children.

人类的历史在很大程度上是与环境斗争的历史。

生活只能向后理解；但它必须向前生活。