Chen Tuan (? A Taoist priest in the early Northern Song Dynasty. His courtesy name is Tu Nan and his pseudonym is Fu Yao Zi. According to the "History of the Song Dynasty", he was a native of Zhenyuan County, Bozhou (now Luyi, Henan Province). In his early years, he was well-versed in Confucian classics such as "The Book of Songs", "The Book of Documents", "The Book of Changes", and "The Book of Rites", and was well-versed in the theories of various schools of thought. He had the great ambition to benefit the world and govern. During the Changxing period of the Later Tang Dynasty (930-933), he took the imperial examination but failed. As a result, he gave up his official career and traveled to famous mountains, seeking immortality and Taoism. He lived in seclusion at Jiushi Rock in Wudang Mountain for over twenty years, practicing breathing and fasting. Later, he moved to the Yuntai Temple on Mount Hua and the Stone Chamber on Shaohua Mountain, and became friends with hermits like Li Qi and Lyu Dongbin. In the third year of Xiande (956) during the reign of Emperor Shizong of the Later Zhou Dynasty, Chen Tuan was summoned to the palace and asked about the art of alchemy and ascension. Tuan replied, "Your Majesty is the ruler of the four seas and should always be concerned about governance. How can you pay attention to the affairs of the yellow and white (that is, the art of alchemy)?" Emperor Sejong appointed him as a censor, but refused to accept it and bestowed upon him the title of "Mr. Baiyun". It is said that he often practiced martial arts and slept for a long time, not getting up for over a hundred days, and was thus known as the one who "slept in seclusion". During the Taiping Xingguo period of the Northern Song Dynasty (976-984), the capital advised Emperor Taizong of Song to "recruit wise men far away, go near , give light taxes to the people, and reward the army." He was highly trusted by Emperor Taizong and was given the title "Mr. Xiyi". Chen Tuan was fond of studying the I Ching and often never put it down. He once created the "Wuji Tu", which was engraved on the stone wall of Mount Hua. He also created the "Xian Tian Tu". Shao Bowen praised Chen Tuan's study of the I Ching as "not requiring textual explanations, but merely using diagrams to illustrate the waxing and waning of Yin and Yang and the changes in the hexagrams." His thoughts had a considerable influence on Neo-Confucianism in the Song Dynasty. It is said that Zhou Dunyi, the founding master of Neo-Confucianism, derived his "Explanation of the Taiji Diagram" from Chen Tuan's "Wuji Diagram". There are many works, but most of them have been lost. In the "Zhengtong Daozang", there is a "Commentary on the Song of Yin Zhenjun Returning the Elixir", titled by Chen Tuan. He is good at calligraphy and his works are four feet long, with thick and vigorous brushstrokes. His script is more than running script and is powerful and forceful. It is said that "Open the Tian 'an horse; The stone-carved couplet "The Dragon Among the Strange Man" was written by him.