In ancient times, there was a man who played the zither very well. One day, he played a tune in front of a cow, hoping that the animal would appreciate his musical skill. Although the melody was beautiful, the cow showed no reaction and simply kept on eating grass. The man sighed and walked away.
The idiom "playing the zither to a cow" is used to describe talking to someone who cannot understand or appreciate what you are saying; it is also used to criticize those who do not consider their audience when speaking.