The thirty-seven Forms of Tai Chi
The 37 Forms of Tai Chi have today become synonymous with the Tai Chi of Professor Cheng Man Ching. Although Professor Cheng never referred to his Tai Chi in this way, but rather a shorter version of the Yang form, it has become a popular title to use. Some still use "Cheng Style Tai Chi", a name first coined by my teacher Wu Kuo Chung but later copyrighted by others. Professor Cheng, however, would certainly not have approved of such a name. In truth, the 37 Forms bear close resemblance to the Yang forms, yet have quite a few subtle differences made by Cheng. As is well known, the primary reason for Cheng to develop this shortened version was after being tasked to teach the Chinese military in a short space of time. He felt the Yang style of 108 forms to be too long. This is also a reason why this style of Tai Chi has been popularised around the world.
Over the years some people have tried to speculate on why Cheng chose the number thirty-seven. Although maintaining the number 37, Cheng did re-arrange the correlation of number to form name at least once. In addition, it is obvious that if each form is counted individually, there would be far more than 37! As far as we know, no-one actually asked Cheng in person why he chose this number. There are at least two feasible explanations that have been proposed. The first is that he based it on the early influences of early Taoists Xu Xuan Ping (許宣平), who taught a form of exercise called “37 Forms” (三十七式), and Li Dao Zi (李道子), who developed a 37 Forms of Tai Chi called Xian Tian Quan (先天拳), "pre-heavenly boxing".
The second explanation follows Cheng's profound interest in the philosophies of Taoism and the Yi Jing (Book of Changes). The number thirteen (13) is used frequently in the Tai Chi classics. For example, the Thirteen Postures (Forms) can be associated with the Eight Trigrams and the Five Phases (metal, water, wood, fire and earth). Similarly, Cheng's early work was called the Thirteen Treatises on Tai Chi Chuan (鄭子太極拳十三篇). The Eight Trigrams exist in two diagrammatic forms, the so-called earlier post-Heaven form (後天八卦) and the later pre-Heaven form (先天八卦). In the post-Heaven form, the trigram Li (fire) and the trigram Kan (water) are in the North and South positions whereas in the pre-Heaven form they are East and West, and North and South are replaced by Qian (Heaven) and Kun (Earth) trigrams. In essence, a state of harmony and balance is symbolised by these exact contrary pairs which also represent the dual energies of Yin and Yang. The trigrams for Li and Kan transition into the trigrams Qian and Kun through exchange of the central line of each trigram.
So what has this got to do with the number 37? In simple terms, the trigram for Li (fire) is also represented by position 3, and the trigram for Kan (water) by position 7 in the pre-Heaven form of the Eight Trigrams. Hence 37 (see diagram). Needless to say, this is a very superficial explanation as the full understanding of the Yi Jing (Book of Changes) and these relationships are extremely complex. In truth, I find it surprising that no-one (as far we know) actually challenged Cheng on this point. Is it important? Probably not, but it is likely to be a source of curiosity for years to come!