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.