Our frustration is greater when we have much and want more than when we have nothing and want some. We are less dissatisfied when we lack many things than when we seem to lack but one thing.
已经拥有许多而想拥有更多的人，其失意感耍大于一无所有而只想拥有一点点的人。另外，只缺一样东西的人也会比缺很多东西的人更不满。
The thing about happiness is that you only know you had it when it's gone.
心理学必须基于可观察的事实，而非推测。