Development economics is ultimately about improving people's lives.
发展经济学最终是为了改善人们的生活。
种树的最佳时间是20年前,其次是现在。
The secret of theory is that truth does not exist.
"Purpose gives meaning to mental activity."
一个人的好名声不是轻而易举就能够得到的;名誉也不是靠欺诈伪装的手段来赢得的。