In his general conduct to them, he manifests the utmost reverence. In his nourishing of them, his endeavor is to give them the utmost pleasure. When they are ill, he feels the greatest anxiety. In mourning for them (dead), he exhibits every demonstration of grief. In sacrificing to them, he displays the utmost solemnity. When a son is complete in these five things, (he may be pronounced) able to serve his parents.

(The Doctrine of Filial Piety)