Natural experiments can provide valuable insights into economic questions.

拥有美好一天的唯一方法是以积极的态度开始它。

年轻人是可怕的，因为怎么能知道他的将来不如我们现在呢？但如果一个人到了四十、五十岁还默默无闻，他也就没有什么可怕的了。

True progress comes when we challenge the status quo and embrace change.

The real challenge is to create something that has meaning beyond its function.

译文：人必须在事情上磨炼，才能立得住;才能做到安静时也安定，行动时也安定。