《后汉书·列传·吴延史卢赵列传》
所以古时候的圣人说： 孝是天之经，地之义，人之行。  君子专心致力于基础工作，基础树立了，道就会产生。
圣人知之，故曰： 夫孝，天之经也，地之义也，人之行也。  君子务本，本立而道生，孝悌也者，其为仁之本与！ 然体在难备，物性好偏，故所施不同，事少两兼者也。
So an ancient sage said: Filial piety is the norm of heaven, the righteousness of earth, and the conduct of man. A gentleman is devoted to his basic duties, and when the foundation is established, the Way will come into being.