Every tree planted today is an investment in tomorrow’s world.
Natural experiments can provide valuable insights into economic questions.
产生好结果的人会自我感觉良好。
Quality is more important than quantity. One home run is much better than two doubles.
在黑暗中寻找光明，是每个作家的使命。
成功不是幸福的关键。幸福是成功的关键。如果你热爱你所做的事，你就会成功。
Where returns are concerned, time is your friend. But where costs are concerned, time is your enemy.
在回报方面，时间是你的朋友。但在成本方面，时间是你的敌人。
