Secrets of Profound Alchemy 通幽诀

The author of Secrets of Penetrating the Mysterious (Tongyou Jue) is unknown.

The text refers to the Tang Dynasty as the "Great Tang State" and Laozi as "True Lord of the Primal Chaos Emperor," indicating it was likely composed by a Taoist priest between the Tang and Song dynasties. The Comprehensive Records of Literature·Bibliographic Survey catalogs this work, and the surviving version—one scroll—is included in the Zhongshu (Various Arts) category of The Dongshen Section in The Daozang.

This text discusses the path of elixir refining, focusing primarily on External Alchemy while also touching on Internal Alchemy. It argues that "the sun and moon—two treasures—are the most spiritual entities of heaven and earth": the sun is the Yang soul, symbolizing fire; the moon is the Yin essence, symbolizing water. Their interaction and transformation through the union of Yin and Yang (water and fire) give birth to cinnabar. Lead and mercury, the core ingredients used in elixir refining, are both derived from cinnabar, hence the text states: "The precious elixir originates from one substance and generates two"; "There is only one path to the great medicine." The Reverted Elixir is "the product of Yin and Yang’s movement and mutual subjugation within a single substance"—that substance being cinnabar.

The text also explains the formation of the Reverted Elixir through the principles of the Five Elements (generation and restriction): "The Dao generates Yin and Yang; Yin and Yang generate the Five Elements; the convergence of the Five Elements forms the Reverted Elixir." "All things are born from water and perfected by fire; fire and metal counteract each other, water and earth restrict each other—thus the great elixir is forged."

Additionally, the text distinguishes between Internal and External Alchemy: "Qi that preserves life is Internal Alchemy; medicines that consolidate the body are External Alchemy. For longevity through ingestion, nothing surpasses the combination of Internal and External Alchemy." "When a person cultivates virtue internally, the harmonious primal Qi permeates their being; nurturing the Dao and concentrating essence into a pearl, they naturally attain longevity."

Most of the content and text of this work is identical to the first scroll of Secret Formulas for the Reverted Elixir at Hand (Huandan Zhouhou Jue). See that entry for further reference.