This is a poem written by Jia Dao, a bitter poet in the Tang Dynasty, and it is also a story of his refining words: it is said that when he was young, he had a poor talent, but he loved poetry very much, and after he got angry with his cousin, he became a monk, claiming that he could not write good poems and would never return to vulgarity. One day, there is an occasional saying: "Birds stay in trees by the pool, and monks push the moon down the door." (titled "Li Ning Living in a secluded room"), in which the word "push" or "knock" should be used, Jia Dao hesitated. Later, Jing Zhao, Yi Hanyu asked about the situation and thought it was good to use the word "knock", because the word "knock" can highlight the depth of the night and the quietness of the environment. Since then, many literati have had heated debates on the use of this sentence "push" or "knock". Mr. Zhu Guangqian, a famous contemporary aesthetician, also expressed his own views in the article "Talking about Words", arguing that the word "push" is good, which is conducive to highlighting the late night, and all the monks in the temple have rested. A monk walked back to the temple, pushed open the door left unlocked and went in.
Yu "push" and "knock" have become an interesting topic of academic debate for thousands of years.