Someone has asked about "heaven plate" yesterday. Here is an excerpt from the course manual "P8 Upgrade Toolkit".
  HEAVEN, EARTH AND HUMAN GUA/ DRAGON 
      In the beginning, luopan had only 8 directions or the 8 trigrams (Qian, Kun, Zhen, Xun, Kan, Li, Gen and Dui).  To make the measurement more precise, the ancients subdivided each trigram (45 degrees) into 3 regions of 15 degrees.  These regions are called “mountains”.
1. People may confuse “heaven” gua must be all “heavenly stems” directions.
            1. People may confuse “heaven” gua must be all “heavenly stems” directions.
2.  24 mountains is another “representation” of post-heaven Bagua—each trigram of the Bagua handles 3 mountains.  So it is essentially another way of “Na Jia”.
3. For the heavenly stems, only 8 stems are used because wu and ji are “earth” and assigned to the center. All 12 earthly branches are utilized.
4. However, there are only 12 + 8 = 20 mountains; we still need four more mountains to “fill” up the 24 directions.
5. Qian, Kun, Gen and Xun, which happens to be at the 4 “corners” of the bagua, are drafted into the 24 mountains.
    3. For the heavenly stems, only 8 stems are used because wu and ji are “earth” and assigned to the center. All 12 earthly branches are utilized.
4. However, there are only 12 + 8 = 20 mountains; we still need four more mountains to “fill” up the 24 directions.
5. Qian, Kun, Gen and Xun, which happens to be at the 4 “corners” of the bagua, are drafted into the 24 mountains.
6. 3 groups of “mountains” are divided according to the location and “purity” :
Heaven gua (yin): zi, wu, mao and yao
  Heaven gua (yin): zi, wu, mao and yao
Heaven gua (yang):  Qian, Kun, Gen and Xun  
        These eight mountains are considered as “pure” because of their location.
The yin group locates on the “4 cardinal points” and the yang group in the 4 corner locations with no mixture of other directional qi
Earth gua (yin): chen, xu, chou and wei (the 4 “tombs” or storages)
Earth gua (yang):  jia, geng, bing and ren 
   Human gua (yin): yi, xin, ding and gui  
  Human gua (yang):  yin, shen, si and hai 
   Characteristics of these guas:
HEAVEN GUA -- specialized prosperity, esp. in fame and social mobility 
 EARTH GUA -- quick and fast prosperity, esp. in academic performance 
 HUMAN GUA  -- long term prosperity, esp. in wealth aspects 
  Copyright 2004 by Ken Lai, All rights reserved
Ken Lai
http://www.kenlaifengshui.com
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