Supreme Inner Alchemy Canon 上洞心丹经诀

The author is unknown.

Judging from its content, it was presumably composed by Taoist priests between the Tang and Song dynasties.

Comprising three scrolls, it is included in the Various Arts category of the Dongshen Section of The Daozang.

This work is a reorganized compilation of excerpts from alchemical texts of the Six Dynasties, Sui and Tang dynasties, including the Inner Chapters of Baopuzi and The Secret Formulas of the Yellow Emperor’s Nine Tripods Divine Elixir Scripture. Its content primarily expounds the essential secrets of Internal Alchemy and External Alchemy techniques.

The first scroll first points out that the supreme essential of immortality lies in treasuring essence and circulating Qi, as well as ingesting medicinal herbs. The core of treasuring essence and circulating Qi consists in returning essence to nourish the brain and absorbing Qi for embryonic breathing. Both practices require choosing an auspicious time to enter a quiet retreat and perform the cultivation, so as to make the "body and mind pure and untainted, and gather Qi to attain gentleness like an infant". One then circulates essence and Qi within the body, ascending it to the Niwan Palace in the brain; or practices breathing regulation and inhalation-exhalation, so that "each breath enters the embryonic state". Practicing this technique can at the least prevent illness, and at the most lead to ascension to immortality. The fundamental principle of ingesting elixirs centers on the Golden Fluid Reverted Elixir, which is refined through nine cycles using only cinnabar as the medicinal ingredient; ingesting it enables one to ascend and become an immortal. For the ingestion of herbal medicines, polygonatum is regarded as the supreme grade. The text states that both cinnabar and polygonatum are generated by receiving the essential Qi of the sun, hence ingesting them can grant longevity to humans.

The second scroll mainly expounds the method of cultivating both internally and externally. Internal cultivation refers to Yin Elixir and Internal Alchemy, which can preserve the physical form and prolong life; external cultivation refers to Yang Elixir and External Alchemy, which can lead to ascension to immortality. "The Three-in-One and the Nine Abodes (the technique of circulating Qi and consolidating essence) are the essentials of internal cultivation; the Reverted Elixir and Golden Fluid are the acme of external refinement." Lacking either Internal or External Alchemy, one "shall not be able to ascend to immortality".

The third scroll primarily narrates the story of the Yellow Emperor ascending to immortality after ingesting the elixir and transmitting alchemical scriptures, as well as the taboos and auspicious guidelines for selecting a day to enter the mountains and compound medicinal ingredients.