The Zhonghe Palace was built in the 18th year of Ming Yongle (1420). It was called the "Huagai Palace" at the beginning of Ming Dynasty. Jiajing suffered a fire. After the renovation, it was renamed the "Zhongji Palace". Now there are still ink stains on the internal components of the ceiling. In the first year of Qing Shunzhi (1644), the Qing royal family entered the Forbidden City. The second year, the Central Polar Temple was changed to the Central Heat Temple. It was the place where the emperor rested before the ceremony. The word "neutral" is taken from the "little": "middle also, the root of the world; and also, the way of the world". Only this house in the three temples can be quietly thought by the emperor. The temple of the middle "allows to hold the middle", for Qianlong royal pen. The book is written, "The heart is only dangerous, the heart is only small, the only perseverance."