《后汉书·列传·左周黄列传》
所以皋陶对答夏禹 ：贵在知人。要使人民安宁，就必须爱人民，这样，老百姓就会爱戴你。 封伯建侯，代皇上爱民，民便因此和穆，讲礼讲让的风俗便由此而兴。
是以皋陶对禹，贵在知人。 安人则惠，黎民怀之 分伯建侯，代位亲民，民用和穆，礼让以兴。
For this reason, Gaotao said in response to Emperor Yu: 'The key is to know people.' To bring tranquility to the people, one must love the people, and in this way, the common people will love you. To grant enfeoffment to marquises and dukes on the emperor's behalf is to show love to the people, and in this way, they will be harmonious and will observe the customs of respecting etiquette and giving way to others.