Once, Emperor Li Longji of the Tang Dynasty dreamed that he was visiting the Moon Palace. He heard Yue Xian playing in the sky and saw a fairy in clothes dancing. The fairy's singing is mysterious and beautiful, and the dancing fairy dances gracefully.
When Li Longji woke up, he remembered something about this dream. Li Longji kept thinking and thinking, and he recorded every thought. Even when he was in court during the day, he was carrying a pair of Yu Di on his back, listening to the minister read the book and practicing secretly below. In order to restore the melody in his dream, Li Longji was almost fascinated, but he still couldn't finish the music. He was very upset.
On one occasion, Li Longji came to Sanxiang Post Station, overlooking Daughter Mountain in the distance. The mountains are undulating and smoky. Li Longji suddenly had many beautiful fantasies. At this moment, he finally remembered all the Yue Xian he had heard in his dream.
Li Longji immediately recorded these tunes on the music score, and created a palace song "Colorful Feathers" suitable for playing in the court.
Li Longji ordered musicians to rehearse "Colorful Feathers" and asked his wife Yang Yuhuan to design the dance. In order to give them a good place to rehearse, Li Longji opened a pear garden in the yard. Yang Yuhuan and Imperial Secretary worked day and night. After a long time, they finally practiced this song and dance.
The next day, Li Longji ordered the performance of this song and dance. Yue Xian played with delicate and colorful feathers, while Yang Yuhuan's imperial concubine and ladies-in-waiting sang and danced like fairies. Li Longji heard these familiar melodies and dances again, as if she had returned to her dream.
Later, this song "Cai Yu" became a classic piece of Daqu in the Tang Dynasty in China and was handed down by later generations.