Once up on a time, there lived a musician called GongMing Yi. He was very good at playing the Zheng, a plucked string instrument. But he also behaved foolishly sometimes.
One day, he saw a cow eating grass in the field near his house. He was inspired by the scene and ran outside to play a tune for the cow. Gongming Yi played beautifully and he himself was intoxicated by the music. But the cow paid no heed to the elegant sounds. It simply focused its attention on eating the grass. Gong Mingyi was surprised to see that. He couldn't understand why the cow was so indifferent to his performance.
Gongming was very angry. But after thinking a little while, he considered that eligant classic music was beyong the cow's understanding, obviously, it was not because his performance was poor. But the cow neither understood nor appreciated his elegant music! Then he played a another melody which mimic the sound of mosquitoes, gadflies and the calf moos to look for its mother, just then the cow stopped grazing and held its ears up, swishing its tail to listen carefully.
From that story comes the idiom "Play the lute to a cow", which implies that someone speaks or writes without considering his audience. In general speaking, the speaker or writer has over-estimated his listeners or readers. In these cases, the idiom mocks the audience rather than the speaker