In Liu Xiang’s Garden of Persuasions (说苑), Lord Mengchang has placed a retainer with the King of Qi. After three years the man has still received no post, and he complains. Lord Mengchang answers: “A thread enters by the needle, but the needle does not make it hold. A woman marries through a matchmaker, but the matchmaker does not make the two close. Your talent must be thin.”
The retainer replies that a fox in the altar of the soil is not attacked, and a rat in the altar is not smoked out, “because of what they rest on.” Lord Mengchang then recommended him to Qi again, and the King of Qi made him chief minister. The idiom 穿针引线, to thread the needle, means to act as a go-between.