对牛弹琴(dui niu tan qin)
Play a tune to the cow
When the one who speaks or writes has not considered his audience well and thus over-estimated their level of understanding.
Once upon a time, there lived a musician named Gong Mingyi who was very good at playing the Zheng, an ancient string instrument. One day, he saw a cow eating grass in the field near his house. He was inspired by the scene and immediately ran out to play a tune for the cow. Gong Mingyi played so beautifully that he was even mesmerized by the music. However the cow paid no attention to the music at all, but simply focused on eating the grass. Gong Mingyi was shocked to see that happening and he wondered,"My music so bad meh?". Of course, we all know that the only reason that the cow had been indifferent to Gong Mingyi's musical performance was because it could neither understand nor appreciate such elegant music.