Li Daochun, also called called Master Ying Chan, alias Yuan Su, was a famous Daoist at the turn of the Southern Song (1127-1279) and Yuan (1271-1368) dynasties. Born in Duliang (in today's Wugang, Hunan province), he also named himself Qing An. As a master of inner alchemy, Li Daochun maintained the idea of the Integration of the Three Teachings. He regarded keeping to the middle as the key to inner alchemy, thinking of the "Middle" as the aperture of the mysterious gate. Therefore he was seen by people of later times as the proponent of the Middle Way sect of inner alchemy. Li was a productive writer and his major works are:
- The Great Collection of Daoist Skills ( 《道德會元》 Daode Huiyuan )
- The Triple Heaven Essence of the Book of Changes ( 《三天易髓》 Santian Yisui )
- Secret Essentials of the Collected Mystery of the Complete Perfection ( 《全真集玄秘要》 Quanzhen Jixuan Miyao )
- Commentaries on the Supreme Sublime Book of Ascending to Mystery, Eliminating Calamities and Protecting Lives ( 《太上升玄消災護命妙經注》 Taishang Shengxuan Xiaozai )
- Commentaries on the Book of Eternal Purity and Tranquility Told by the Supreme Venerable Sovereign ( 《太上老君說常清靜經注》 Taishang Laojun Shuo Chang )
- Li's disciples edited his speeches into the books Quotations of Qing An, Master of Yin Chan ( 《清庵瑩蟾子語錄》 Qing An Yingchan Zi Luyu ) and
- Essays on Harmony ( 《中和集》 Zhonghe Ji ).