The Book of Master Tuo Yue
The 1-volumed Tuo Yue Zi ( 《橐籥子》 Tuoyue Zi ) with the Inner Chapter of Yin Elixir ( 《陰丹內篇》 Yindan Neipian ) as an appendix does not record its author's name. It tells about the theory of heavenly way, Yin and Yang, five agents and the eight trigrams to prove the way of the golden elixir. Essence of the trigrams, symbolized by the moon, is the greatest way. The book, combining images of the moon with trigrams, draws six charts to illustrate the way of longevity. The Inner Chapter of Yin Elixir explains the way of elixir with the theory of the Book of Changes. It points out: Yang contains Yin and thus Trigram Kan has Yang as its inside and Yin outside. Yin contains Yang and thus Trigram Li has Yin as its inside and Yang outside. Only through refining and discarding the Yin with fetched Yang, can one become a man of pure Yang. This book about the way of inner alchemy interpreted by means of the Book of Changes, collected in the Supreme Clarity Section of the Daoist Canon of the Zhengtong Era, is valuable for the study of Daoist inner alchemy.