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?"

晋平公令人制作了一张琴。琴上的弦，粗细一个样，大弦、小弦没有区别。琴制作好以后，晋平公让乐官师旷来调音。师旷调了一整天，也没调出个曲调来。

晋平公责怪师旷不会调琴。师旷解释说: “一张琴，大弦就好比国君，小弦就好比臣子。大弦小弦各有各的功能，它们彼此配合，才能合成音律。大弦小弦有条不紊，才能奏出和谐悦耳的音乐。您现在把琴弦做成大小不分，破坏了它们应有的系统性与规律性。这样的琴，您让我怎么调呀?”