《韩非子·解老》
因此父子之间的礼纯朴自然而不拘形式，所以说，礼是淡薄的。一切事物不能同时旺盛，阴阳就是这样；事理总是正反相互排斥的，威和德就是这样；实情深厚的外貌就淡薄，父子之间的礼就是这样。
是以父子之间，其礼朴而不明，故曰： 理薄也。 凡物不并盛，阴阳是也；理相夺予，威德是也；实厚者貌薄，父子之礼是也。
Therefore family affection is simple and natural not bound by formality, thus, propriety is simple. All things cannot be prosperous at the same time , this is like yin and yang; the truth of matters is always to repel each other, authority and virtue are like this; a sincere and deep feeling is simple, family affection is like this.