In ancient times, there lived a musician named Gong Mingyi. He was a master of the Zheng, a plucked string instrument. Unfortunately, his rash behavior often led him astray.
One day, he saw a cow grazing in a field near his house. He was inspired by the scene and ran outside to play a tune for the cow. Gong Mingyi played beautifully, finding himself intoxicated by the music. But the cow paid no heed to the elegant sounds, simply focusing its attention on eating the grass. Gong Mingyi was surprised at this and could not comprehend the cow’s flippant indifference. He felt that since his performance had been masterful, this means that the cow neither understood nor appreciated his elegant music!
From that story comes the idiom "To play the lute to a cow", which implies that someone speaks or writes without considering his audience. Generally speaking, it means the speaker or writer has over-estimated his listeners or readers. In these cases, the idiom mocks the audience rather than the speaker.