In the ninth year of the Kaiyuan era of the Tang Dynasty (721), a solemn ceremony was held in the palace of Luoyang, the eastern capital of the Tang Dynasty. Li Longji, Emperor Ming of the Tang Dynasty, received the Taoist teachings and became a Taoist emperor. It was the famous Taoist Sima Chengzhen who taught him the Taoist scriptures. Sima Chengzhen (647-735), born in Wenxian County, Hanoi Prefecture (now Wenxian County, Henan Province), is a master of the Shangqing Sect. Although he came from an official family, he was not good at being an official and learned the Tao well. When he was 21 years old, he entered Mount Song and worked as Pan Shizheng. He learned the Shangqing Scripture, Rune, Valley Piercing, Guidance and Bait Taking. Sima Chengzhen studied very hard. When he first learned the Tao, "he put a hundred pieces of rubble on his desk, and every time he read a volume of the Duren Sutra, he moved a piece of tile under the desk." He used this method as a mark and read hundreds of volumes every day. After Sima Chengzhen completed his studies, he visited Maoshan Mountain, Wangwu Mountain, Hengshan Mountain and other famous mountains. Later, he settled in Tiantai Mountain, Zhejiang Province, where he called himself "Baiyunzi". Sima Chengzhen is famous for his character and scholarship. Several emperors have asked him to enter the capital and were honored as imperial teachers. When Empress Wu heard of her high reputation, she invited her to Luoyang, the eastern capital, to give her hand in praise. In the second year of Jingyun (711), Li Dan, the brother of Ruizong, welcomed Sima Chengzhen to the Chang'an Palace in Western Beijing and asked about the number of yin and yang skills and self-cultivation. Sima Chengzhen said with the idea of Laozi's inaction: "The Tao is damaged day by day, and it is also damaged, so that nothing is done.". Later, the Ruizong did abdicate the throne to his son Li Longji (namely, Emperor Xuanzong of the Tang Dynasty), which embodied the Taoist spirit of non competition and inaction. Sima Chengzhen declined Ruizong's invitation to stay in Chang'an to assist the imperial court and begged him to return the mountain. The Emperor Ruizong knew its elegant and good music, so he gave it as a gift, such as a zither, and wrote an edict to express his parting with the words "white clouds are leisurely, as far as the sky". More than one hundred people were sent off by Gongqing in the court. Among them, Lu Zangyong, a good friend, once hid in Zhongnan Mountain. Later, he was an official in an important position. He was known as a "hermit". Seeing that General Sima Chengzhen returned to the Tiantai Mountain, he pointed to Zhongnan Mountain and said to him: "There are many advantages in this. Why the Tiantai Mountain?" Sima Chengzhen said in a humorous and cynical tone, "It is a shortcut for officials to view it as a servant.". The "shortcut" has become a well-known allusion. Sima Chengzhen had no intention of becoming an official. It is said that Ruizong repeatedly ordered him to leave the mountain. He regretted leaving more than ten miles away. Later generations called this place "Sima Regret Mountain" (now north of Tiantai Mountain in Taizhou), which is the 60th blessed place of Taoism. Emperor Xuanzong believed in Taoism and had the closest relationship with Sima Chengzhen among the emperors of the Tang Dynasty. He adopted a series of policies to promote the development of Taoism, making Taoism enter its heyday. First of all, raise the status of Lao Tzu, the founder of Taoism, respect the Tao Te Ching as the first of all the classics, and personally annotate it, and issue it to the whole country; I have been awarded the title of "Great Sage" for several times, so as to be "Emperor Xuanyuan of the Golden Palace". Secondly, it stipulates the system of Tao Ju, which uses the "Four True Classics" (namely, "Lao Tzu", "Zhuang Tzu", "Lie Tzu", and "Wen Tzu") to learn from others; And set up Chongxuan Hall, Doctor of Metaphysics, etc. most