Ping Gong of Jin ordered someone to make a stringed musical instrument. The strings of the instrument were of the same size, with no difference between the small strings and the large string. After the instrument was made. Ping Gong of Jin asked Shi Kuang, an official in charge of music, to tune the instrument. Shi Kuang spent a whole day doing it, but failed to tune out a melody.

Ping Gong blamed Shi Kuang for his incompetence. Shi Kuang explained: "The large string of a musical instrument is like the king of a state, and the small strings are like his subordinates. The large string and the small strings have their own functions. Only by coordinating with one another can they compose temperament, and only by being orderly can they play harmonious and pleasant music. Now there is no difference in size between the large string and the small strings. This ruins the system and regularity which they should have. How can I tune an instrument like this?"

晉平公令人制作了一張琴。琴上的弦，粗細一個樣，大弦、小弦沒有區別。琴制作好以后，晉平公讓樂官師曠來調音。師曠調了一整天，也沒調出個曲調來。

晉平公責怪師曠不會調琴。師曠解釋說: “一張琴，大弦就好比國君，小弦就好比臣子。大弦小弦各有各的功能，它們彼此配合，才能合成音律。大弦小弦有條不紊，才能奏出和諧悅耳的音樂。您現在把琴弦做成大小不分，破壞了它們應有的系統性與規律性。這樣的琴，您讓我怎么調呀?”