When Chen Sheng was young, he worked on the land as a hired hand. Once, he stopped ploughing and stood upon a ridge in a gloomy mood for a long time. Then he said to his fellow workers: "If any one of us becomes rich and famous in future, let him not forget the others." His fellows laughed at him and said: " You are only a hired laborer; how can you become rich and famous?" Chen Sheng sighed: "Oh, how can a swallow know the aspirations of a swan?" Afterwards, Chen Sheng led an uprising against the rule of the Qin Dynasty and was made king.

Later, the phrase became used to comment on mediocre people who cannot understand people with great ambitions.