The man of Zheng buys shoes is a fable from the pre-Qin era, which comes from "Han Feizi". It is not only an idiom, an allusion, but also a fable. It tells the story of the people of Zheng who believed too much in "measures" and could not buy shoes. It reveals the Zheng people's habit of being dogmatic and relying on data. It is often used as a metaphor for people who are rigid in doing things and cannot be flexible. It tells people to seek truth from facts when encountering problems, to be flexible and not to stick to dogma.

The original intention of buying a casket and returning pearls is that the wooden box bought to contain pearls is returned to the pearls. It is a metaphor for a buyer making a poor choice, and the secondary things are better than the primary ones. Buying a casket for a pearl is a derogatory term. Words similar to it include: putting the cart before the horse, putting the cart before the horse, taking advantage of others' salary, sacrificing the foundation for the last, and improper choice.

A doctor buys a donkey, doctor: an official name in ancient times. The doctor bought a donkey and wrote a three-piece contract, but there was no word "donkey" in it. The metaphor is wordy, full of nonsense, and misses the point. The sarcastic writing is long and lengthy but misses the point.