This idiom comes from the later Han Dynasty. Literally, the old cow licks the hair of the young cow. In animals, this is a way to express her love. The old cow used this move to express her love. Now it is a metaphor for parents' concern and love for their children. As the saying goes, parents' love for their children is far-reaching, which coincides with the meaning expressed by their deep affection. Parents' love for their children is always unconditional, and love is deep and restrained, silently helping children go further and smoothly on the road of life.
To sum up, partridge affection and calf affection are both commendatory idioms, but the objects they express are different. There are also many idioms or poems in ancient poetry that express emotions with the help of animals and plants. For example, collusion, wolves and wolves are bad animals, to express that two bad guys collude with each other and do some shady bad things; Another example is the cunning fox, although its strength is limited, it will also use the tiger's power to intimidate the surrounding animals. This idiom means to suppress and intimidate others with the help of their power and power.