我們期望晚餐不是出自屠夫、啤酒商或面包師的仁慈，而是出自他們對(duì)自身利益的考慮。
It is not from the benevolence of the butcher， the brewer， or the baker that we expect our dinner， but from their regard to their own interest.
The simplest solutions are often the most elegant.