Under what historical background did Su Shi write a night tour of Chengtian Temple?

This article was written in the sixth year of Yuanfeng in Song Shenzong (1083). At that time, the author had been demoted to Huangzhou for four years. In July of the second year of Yuanfeng, the famous "Wutai Poetry Case" in history, Li Ding picked out Su Shi's poems about the new law and said that he slandered them. In August, he was arrested and imprisoned. After a long trial and torture, I almost lost my mind. 1February, the author was released from prison and demoted to Huangzhou to be an assistant forever, but he was not allowed to "sign books to do business", that is to say, he was an idle official with positions but no rights. In this case, the author wrote this essay, describing the scenery of the moonlit night beautifully and recording a fragment of his life at that time.