"Buy the pearls back" means a wooden box, which comes from Han Feizi. The original intention was to buy jewelry, leaving only beautiful boxes and no real high-value jewelry. It is often used to describe returning pearls when you buy a briefcase and have no good eyesight.

Moral of this idiom: Zheng people only see exquisite wooden boxes and give up precious jewels. It can be seen that things must be clearly defined, and people who buy gifts and return pearls cannot only pay attention to the appearance of things and not see the essence of things. Only by seeing the essence of things clearly and prioritizing can we make appropriate choices. The idiom originally meant to put back the wooden box bought to hold pearls; The metaphor is improper choice, and the secondary things are better than the main ones.