The Principles of Alchemy

The Seal of the Unity of the Three (Cantong qi), Poem 22

Cantong qi: The Seal of the Unity of the Three

Reproduced from:

The Seal of the Unity of the Three: A Study and Translation of the Cantong qi, the Source of the Way of the Golden Elixir

Fabrizio Pregadio
Golden Elixir Press, 2011
Paperback ● Hardcover ● PDF (abridged)

Under an allusive poetical language and thick layers of images and symbols, the Cantong qi hides the exposition of the teaching that gave origin to Taoist Internal Alchemy (Neidan). In addition to a complete translation, this book contains a detailed introduction to the history and teachings of the Cantong qi, explanations of each of its sections, and notes on its verses.

Chrome bullet   This page is part of a series on the Seal of the Unity of the Three. See the complete index.


知白守黑、神明自來。白者金精、黑者水基。 5 水者道樞、其數名一。陰陽之始、玄含黃芽。五金之主、 10 北方河車。故鉛外黑、內懷金華。被褐懷玉、外為狂夫。


1-2"Know the white, keep to the black,"
 and the Numinous Light will come of its own.
3-6White is the essence of Metal,
 Black the foundation of Water.
 Water is the axis of the Dao:
 its number is 1.
7-10At the beginning of Yin and Yang,
 Mystery holds the Yellow Sprout;
 it is the ruler of the five metals,
 the River Chariot of the northern direction.
11-14That is why lead is black on the outside
 but cherishes the Golden Flower within,
 like the man who "wears rough-hewn clothes but cherishes a piece of jade
in his bosom,"
 and outwardly behaves like a fool.

Notes to Poem

Alchemy seeks the principle that gives birth to, and is hidden within, the manifest cosmos. Among the emblems of the Book of Changes, this principle is represented by the solid Yang line contained within Kan ☵ (Water), which originally belongs to Qian ☰. Alchemically, it is represented by the True Lead found within "black lead," or native lead.

The opening sentence, borrowed from the Daode jing, states that one should "keep to the black" in order to "know the white." Black (Yin) represents the agent Water, the outer Yin lines of Kan ☵, and native lead; it is the world in which we live. White (Yang) represents the agent Metal, the inner Yang line of Kan, and True Lead; it is the One Breath sought by the alchemist. "Keeping to the black" and "knowing the white" generates the Numinous Light (shenming), which in the alchemical metaphor is the Elixir.

Therefore the precelestial Breath is to be sought within Water. As a cosmological principle, Water is the first of the five agents (here called the "five metals"); it is "the beginning of Yin and Yang," and is represented by number 1 and by the northern direction. Because of its primal position within the cosmos, Water is the "axis of the Dao," and all changes and transformations derive in the first place from it. For the same reason, Water is also the element that supports the River Chariot (heche), the vehicle that transports the One Breath (Metal, True Lead, True Yang) back and forth in its cycles of ascent and descent within the cosmos.

Water is the "mystery" (xuan): it stands for obscurity, the north, and black lead, but it holds light and, being the "axis of the Dao," is intimately connected to the center. In alchemical language, this hidden principle is referred to as the Yellow Sprout (huangya), a term that connotes both the essence of Metal (True Yang) found within Water (Yin), and the first intimation of the birth of the Elixir (denoted as "yellow" for its association with Soil, the agent that represents the center). Analogously, lead is black outside, but harbors the white and luminous Golden Flower (jinhua) within. Quoting another passage from the Daode jing, the Cantong qi likens the authentic principle hidden in the darkness of the world to the treasure concealed by the saintly man, who disguises himself as a common mortal.

Notes to Verses

1. "Know the white, keep to the black." This sentence is quoted from Daode jing, 28: "Know the white, keep to the black, and be a mold for the world. If you are a mold for the world, the constant virtue does not depart from you, and you return to the Ultimateless."

2. And the Numinous Light will come of its own. Compare Daode jing, 73: "The Dao of Heaven does not contend but is good at overcoming, does not speak but is good at responding, is not summoned but comes of its own, seems to be slack but excels in planning."

3-4. White is the essence of Metal, Black the foundation of Water. For several commentators, "white" stands for True Lead; for others, it means either mercury, or silver, or gold. These varying views reflect different configurations of the alchemical emblems, in whose contexts the same principle can be represented by different terms and symbols. "White," in all cases, alludes to the authentic principle contained within the "black." Being the True Yang within Yin, this authentic principle is the opposite of black lead, and therefore is called True Lead. For the same reason, it may be called "mercury," which in Chinese alchemy stands in a polar relation to lead. Because of its white color, it can also be called "silver," in contrast to black native lead. Finally, since True Yang is the precelestial One Breath, it may be called "gold," the metal that more than any other represents the Elixir.

6. Its number is 1. Compare the "Monograph on the Pitch-pipes and the Calendar" in the History of the Former Han Dynasty: "By means of number 1, Heaven generates Water. By means of number 2, Earth generates Fire. By means of number 3, Heaven generates Wood. By means of number 4, Earth generates Metal. By means of number 5, Heaven generates Soil" (Hanshu, 21A.985; the same passage is also found in several other texts). These are the so-called "generation numbers" (shengshu) of the five agents. The "accomplishment numbers" (chengshu) are obtained by adding 5 to each "generation number." See table 4.

9. It is the ruler of the five metals. The five metals are gold, silver, copper, iron, and lead. Here they are meant as mere emblems of the five agents: Water is the first of the five agents, and lead, which is related to Water, is "the ruler of the five metals."

10. The River Chariot of the northern direction. In Neidan, River Chariot refers to path of the circulation of Breath (qi) through the renmai and dumai vessels, respectively running along the back and the front of the body. This circulation is analogous to the circulation of the One Breath in the cosmos along the cycles of time and the compass of space.

13. Like the man who "wears rough-hewn clothes but cherishes a piece of jade in his bosom." This sentence is quoted from Daode jing, 70: "It is only because they have no understanding that they do not understand me; but since those who understand me are few, I am honored. Thus the saint wears rough-hewn clothes, but cherishes a piece of jade in his bosom."