保卫国家政权，是那些君主和臣子等享受俸禄的人谋划的事；保卫整个天下，即使是地位低微的普通百姓也有责任参与。

Every tree planted today is an investment in tomorrow’s world.

The ability to associate depends, in turn, on the degree to which communities share norms and values and are able to subordinate individual interests to those of larger groups.

如果你一直重读上一章，就无法开始人生的新篇章。