Sunday, 22 May 2016

I Ching Top

Using a top is a great way to generate random events. In 2001, Malford W. Goldberg patented an I Ching Top which he had started selling on his ichingtop.com site since the year before.
It was advertised as a reconstruction of an ancient method for casting hexagrams supposedly in use during the Han dinasty as part of many occult rituals.
The site is no longer on line (the latest archived version on the Internet Archive is dated November 2002) and the product doesn't seem to be available anymore. In his article on I Ching related patents, Joel Biroco provides more infomation on this method.

Actually, I've not seen any other reference to tops used in ancient times for divination in conjuction with the I Ching but I believe it is an interesting idea, worthy to be preserved. The I Ching Top was used as follows:
  1. Spin the top;
  2. Draw the line which is closer to the axis on the side the top stopped on;
  3. Repeat steps 1-2 drawing hexagram lines from bottom to top.
The image below shows the front and the back of the top:
 

The drawings on the faces may suggest other methods for casting hexagrams (for example one trigram at the time).

Probabilities

Looking at the image above, counting the possible outcomes, is clear that the probabilities are the same of the three coins method.
Prob(6) = Prob(9) = 1/8 = 12.5%
Prob(8) = Prob(7) = 3/8 = 37.5%
Prob(yin) = Prob(yang) = 1/2

Variations

On Thingiverse I've found another I Ching top which only allows casting the hexagram one trigram at the time. The 3D model is freely downladable.


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