Reproduced from the Introduction to:
Fabrizio Pregadio, 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
Golden Elixir Press
The five agents are Wood, Fire, Soil, Metal, and Water. They carry the Original Breath issued from the Dao into the cosmos, and represent its differentiation in the world of multiplicity.
In a different but related function, moreover, the five agents make it possible to classify items belonging to different sets—directions of space, segments of time cycles, numbers, colors, planets, minerals, and organs of the human body, to mention only a few—into five emblematic categories, in order to show the relations that occur among items belonging to the same category and among those that belong to different categories.
For example, with regard to the first type of relation, the agent Wood associates the east, the spring, the numbers 3 and 8, the color green, the planet Jupiter, and the organ liver with one another. With regard to the second type of relation, spring and summer, respectively associated with Wood and Fire, exemplify two different states of the Yang principle (the same it true, therefore, of Jupiter and Mars, the liver and the heart, and so forth).
© Golden Elixir Press