The Fire Phases
Foundations of Internal Alchemy: The Taoist Practice of Neidan, by Wang Mu, page 79
According to the alchemical texts, the main requirement at the stage of “refining Essence and transmuting it into Breath” is that the Yang Essence be refined and transmuted. The hexagram Fu ䷗, formed by Earth ☷ and Thunder ☳, is called “the birth of initial Yang” (yiyang sheng). This Yang should be collected and refined by going through the six Yang stages until it reaches the pure Qian ䷀. The firm Yang grows until it culminates, and when something culminates, it is followed by an inversion. This is a metaphor to indicate that although the Yang Essence is already abundant, it is still a material entity and thus cannot form the Medicine; it should first be turned from firm to yielding, and then be transmuted.
Therefore, as the Essence goes through the six Yin stages, it is progressively transmuted until it exhausts its firm, material Breath, and forms a “Breath” made of the union of Essence and Breath.
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