What do the two idioms mean: the crow feeds back and the lamb kneels and milks?

Crow feeding back means that when the little crow grows up, the old crow can't fly and can't find food by himself. Little crows will look for food to feed their mothers in turn. The lamb kneels and suckles means that the lamb kneels and suckles. He knew that his mother fed him with milk, and he thanked her for breastfeeding on his knee.

Both words imply filial piety. Animals know how to be grateful to their parents and honor their elders, not to mention people.

Extended data:

"Lamb kneels and suckles" comes from the old adage "Augmented Sage", the original text is "A sheep kneels and suckles, and a crow feeds back".

"Crow feeds back" comes from "Compendium of Materia Medica: Poultry Department": "Second time, this bird is born, and its mother feeds for 60 days, and if it is long, it feeds back for 60 days."

It is said that the crow grew up under the care of its mother. When her mother was old and weak, unable to eat or blind and unable to fly, her children would look around for delicious food, bring it back to their mouths, and feed it mouth to mouth until the old crow died and couldn't eat any more.

References:

Baidu encyclopedia-crow feeds back