译序原文：
人类要想使自己真正达到不争、节欲、处柔的境界，以便获得真正的幸福，有一个简便的途径，那就是明白知足常乐的道理。老子曰：“知足之足，常足矣”。幸福是什么？幸福就是一种自我满足的感觉。获得这种感觉的途径有两条。一条是通过外部的刺激，例如最大程度地合法地满足一个人的欲望的办法来获得；一条是通过内省，例如彻底明白幸福不过是一种自我满足的感觉这个道理，因此尽可能少地依赖外部刺激而直接借助于理性的悟解而获得那种感觉。也许，知足常乐的思想是人类关于幸福的最伟大的思想。很难说究竟是谁在人类历史上第一个发现了它。但是，老子对这个思想的阐述是确切的、实实在在的。单是这一点，就足以使老子跻身于人类史上最伟大的思想家之列。（划线159字）
（辜正坤，《老子道德经》，译序，北京大学出版社，1995）
译文：
What is happiness? Happiness, in my opinion, is nothing but a sense of self-satisfaction. There are two ways to gain that feeling: one way is to gain it by exposing one’s body to external stimulations, say, satisfying one’s desires; the other is to gain it through an introspection of the truth that happiness is only a consciousness of self-satisfaction, and thus happiness be gained by resorting to reason and illumination while reducing external simulation to a minimum. Perhaps, the idea of being content with one’s lot is the greatest thought ever born of man’s brain. (辜正坤 译)