Inner Alchemy in Four Hundred Words 金丹四百字

Composed by Zhang Boduan during the Song Dynasty and annotated by Huang Ziru in the Southern Song Dynasty. Consisting of one scroll, it is included in the Tai Xuan Section within the Taoist Canon (The Daozang).

It is also included in Volume 6 of Ten Books of Cultivating Perfection (Xiuzhen Shi Shu), with slight textual differences from the version in the Taoist Canon.

Inner Alchemy in Four Hundred Words

A preface by the author precedes the main text. The core content consists of five-character verses, totaling four hundred words. Both the preface and the verses elaborate on the essentials of Internal Alchemy (Neidan), sharing the same purport as Zhang Boduan’s Wu Zhen Pian (Awakening to Truth).

The book states: Refining gold with fire to return to the root and revert to the origin is called the Golden Elixir. The key to refining the elixir lies in aligning the body and spirit with the Kan ☵ (trigram of water) and Li ☲ (trigram of fire), upholding the Unity and abiding in the middle, cultivating the primal essence and nurturing purity, drawing the innate primal mixed Qi (Vital Energy), gathering the Five Elements, and harmonizing the Four Symbols. This enables the five energies of the heart, liver, spleen, lungs, and kidneys to converge toward the primal source, and the three treasures of essence, Qi, and spirit to gather at the top of the head. Thus, spirit, soul, ethereal soul, and intent become firm and impermeable, blending into a single Qi—formless and shapeless, named Emptiness. From Emptiness emerges existence: an "infant" is nurtured, and the Golden Elixir is formed.

In summary, the practice is based on primal essence, primal Qi, and primal spirit. The harmonization of lead and mercury, and the manipulation of water and fire, all follow precise measurements and principles. Furthermore, one must understand the mysterious "Xuan Pin" (Profound Vulva) orifice within the body—where the alchemical substances, fire timing, meditation retreats, embryo formation, and transcendence all take place. However, the location of this orifice can only be known through oral transmission and heart-to-heart instruction.

The verses are quite obscure in meaning, while Huang Ziru’s annotations are relatively detailed and clear. A postscript by Huang, written in the Xinchou year of the Chunyou reign (1241 CE), is appended at the end of the book.