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Yu Yan's Diagram of the Fire Phases

Fabrizio Pregadio

This diagram comes from the Yiwai biezhuan (The separate transmission of the Book of Changes), written by Yu Yan in 1284. This work contains several cosmological diagrams, followed by passages drawn from the Book of Changes and commented through quotations from the Zhouyi cantong qi.

Diagrams like this have a long history in China. They are used to show the correspondences between different ways of marking space and time, e.g., the directions, the twelve primary hexagrams (each associated with one month), the days of the moon cycle, the lunar mansions, and so on. In addition, each discipline based on the laws of cosmology uses these diagrams in different ways, e.g., for astronomical calculation and divination. In Chinese alchemy, the correspondences shown by these devices are used to establish the "fire phases" (huohou), i.e., the cycles of firing in external alchemy (waidan) and the cycles of the circulation of the primary components of the person in internal alchemy (neidan).

From the outer to inner rings, each ring of the diagram drawn by Yu Yan shows:
fire phases
  1. The twentyeight lunar mansions (xiu)

  2. Sixty of the sixtyfour hexagrams

  3. The thirty days of the lunar month

  4. The twentyfour periods of the year

  5. The twelve "sovereign hexagrams" (pigua)

  6. The twelwe Branches of the Earth (dizhi)

  7. Six of the eight trigrams

  8. The four seasons

  9. The four emblematic animals (White Tiger, Red Bird, Green Dragon, and Dark Warrior)

In the innermost circle are the seven stars of the Great Bear. Its circular movement determines orientation (space) and sets in motion the various cycles of time.

As noted above, this diagram shows only six of the Eight Trigrams and only sixty of the Sixtyfour Hexagrams. The remaining two trigrams and four hexagrams are:

Qian and kun represent the male and female principles that generate the cosmos, respectively. Kan and li contain those principles hidden within themselves once the cosmos is generated. These four trigrams and hexagrams are at the center of time and space and do not enter the cycles of time; therefore they are not shown in this and similar diagrams.

The twelve "sovereign hexagrams" in the fifth ring represent the rise and ascent of Yin and Yang. This movement, sometimes referred to as "ebb and flow" (xiaoxi), is apparent if the hexagrams are shown in the following way:

12 Sovereign Hexagrams

There are several diagrams similar to the one esablished by Yu Yan. One of them was drawn by Peng Xiao in 947; for a reproduction and analysys see Joseph Needham et al., Science and Civilisation in China, vol. V:5 (Cambridge, 1983), pp. 55-58.

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Created: October 10, 1995 - Last revised: June 21, 1997
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Copyright (C) 1995, 1996, 1997 Fabrizio Pregadio