Chou Wen-chung
Chou Wen-chung’s modal system: the Basics
[continued]
This reveals that the “trigger” (or at least one of the triggers) for a Yin-Yang exchange may very well be the half-step, i.e., the pien tone. A Yin line of C-D can change its modality by raising the second note (D) by a half-step and turn it into a C-E
Yang line. By applying the pien tone (the raising or lowering by a half-step) a Yin line can turn into a Yang line and vice versa. This is also the way one pien mode is changed into another. This convenient and economic gesture of transformation reflects the “terseness in realization” aspect of Chou’s music/system.
Just as there are Eight Trigrams there are eight pien modes in Chou’s system:
| Chou’s pien modes | I Ching trigrams |
|---|---|
| Heaven | Chien |
| Lake | Lui |
| Sun | Li |
| Thunder | Zhan |
| Wind | Sun |
| Water | Gan |
| Mountain | Kan |
| Earth | Kun |
Legend has it that the Eight Trigrams were invented by Fuxi, one of the fabled leaders of ancient Chinese civilization. But it was the founder of the Chou dynasty, Emperor Wen, who devised the sixty-four hexagrams and their accompanying aphorisms which made up the original I Ching (hence the I Ching is also known as Chou I).
Chou’s answer for the hexagrams is his sixty-four Modal Complexes. Just as the hexagram is a stacking of two trigrams one on top of the other, Chou’s Modal Complex is a succession of two pien modes which satisfies the following three conditions.
- The two modes must have opposite contours, i.e., an ascending mode followed by a descending one, or vice versa.
- The principal notes upon which the two modes are built must be a half-step apart. For example, a C ascending mode is to be followed by a C
descending mode, or a C descending mode to be followed by a B ascending mode. - The two modes are related in terms of their intervallic structures. There are at least three different ways the two modes can be related but the most interesting and probably most often used relation is that of symmetry — that is, a <100> Thunder mode is to pair with a <001> Mountain mode — the first line of the first mode is the same as the last line of the second; the middle line of the first mode is the same as the middle line of the second; and the last line of the first mode is the same as the first line of the second, as shown in Ex. 5.