During the Jiaqing period of the Qing Dynasty, Yao Nai, a native of Tongcheng, Anhui Province, was a representative writer of Tongcheng School and wrote Sikuquanshu.

Yao Nai's writing at his desk for a long time leads to proctoptosis, which not only affects his writing, but also affects his physical and mental health. Diagnosed by traditional Chinese medicine, it is considered that this is the cause of stagnation of middle qi and deficiency of Yuan Qi. Therefore, under the guidance of a Taoist priest, Yao Nai often went for a walk and sightseeing in a quiet and elegant place in the natural pine forest, especially with his hands clasped on the trunk (this is the name of cherishing the body), and suppressed and treated himself by "constantly lifting his anus". So, he added a porch next to the big pine tree in Zhongshan Academy, hoping to "cherish the porch". Call yourself Mr. Bao.