This is for members who are using Meihua Yishu 梅花易數, ‘Plumblossom Numerology’ and follow Da Liu’s book I Ching Numerology. I got an email from a reader, asking about a problem with the Later Heaven formula (p. 48-49). He wrote,
“The later heaven formula particularly attracts me due to its especially poetic way of reading situations but I noticed that for the moving line Da Liu provides the method of adding the numbers of the trigrams together (according to the later Heaven sequence) and then subtracting 6 if the sum is greater than 6. This troubled me as it means that each hexagram can only have one possible moving line as the trigrams have fixed values with no possibility of variation according to the situation. So for instance hexagram 44 Kuo will always have the fourth line as a moving line- and the other five will never occur. Does this accord with Shao Yong’s method?”
And I replied,
I think Da Liu might be wrong here. The original Meihua Yishu book says,
后天端法：以物为上卦，方位为下卦，合物卦之数与方卦之数，加时数以取动爻。
The Houtian rule: use Object as upper trigram, and Direction as lower trigram. Combine their numbers and add the number of the time to it to obtain the moving line.
I checked this with Jack Kuo’s website, which contains the original MHYS book with Jack’s commentary (Jack also wrote an excellent book about MHYS).
Jack gives as an example:
例如，午時見到一個老人家從東北方過來，乾為夫，老人家即為乾象（若是老婦人則取坤）。東北方則是艮卦，因此取卦為天山遯，遯卦。 乾於數為 1，艮為 7，午時為 7（這裡用的數也是先天數），1 + 7 + 7 = 15，除以 6 餘 3，因此變爻為 3。 此卦為遯卦九三爻變，為遯之否。
For example, at hour wu 午 I encounter an old man who is approaching from the North-East. Trigram Qian ☰ is a man, and an old man therefore is represented by trigram Qian (if it were an old woman it would have been trigram Kun ☷.) The North-East is trigram Gen ☶, so the result is hexagram 33 (Heaven above Mountain.) The number of Qian is 1, Gen is 7, hour wu is 7 (the numbers used here are the Xiantian numbers). 1 + 7 + 7 = 15. Divided by 6 the remainder is 3, which means that the moving line is line 3. The hexagram is hexagram 33, with a moving line at 3, changing to hexagram 12.
In other words, if you want to use the Later Heaven formula correctly: don’t forget to add the hour.
