The flow and accumulation of energy in the body during the performing of Tai Chi can be represented, in an accurate and enlightening way, by means of twelve hexagrams that are collectively known as the "waxing and waning cycle". This cycle has been widely used for theoretical purposes in several different fields of Chinese traditional knowledge; including acupuncture, meditation and the calendar. The cycle itself is fairly simple to describe, the ideas of "waxing" and "waning" having to do with the orderly increase and decrease of the number of unbroken (yang) lines in the hexagrams involved.

The cycle may be considered as starting from the hexagram number 24, which has a single yang (unbroken) line in the lowest place, and all of its remaining upper lines are yin (broken) . By continuing further stages into the cycle it can be seen that the yang lines move successively higher up the hexagram, and the lines below them remain yang. Thus, the second hexagram in the cycle is number 19 (bottom two lines are yang); the third hexagram is number 11 (with three yang lines in the first three places) ; the fourth hexagram is number 34; the fifth hexagram is number 43; the sixth hexagram is number 1 (all lines are yang) . This completes the "waxing" part of the cycle, after which the "waning" begins.

Through the use of your imagination it is not difficult to see how this pattern of hexagrams can be used to give an accurate account of the regular cyclic processes of nature, such as the phases of the moon and seasons of the year. What is perhaps less obvious, but no less useful once the idea is understood, is to apply the same principles to the description of cyclic processes within the body. In fact, the flow of energy during the playing of the Tai Chi Form is a particularly good example of such an application.

To begin with, it is sufficient to consider the very first movement of the Form, in which the arms are raised while the knees are slightly straightened, and then the arms lowered as the knees are bent once again. The movement of the arms and leg action in this posture is designed to guide the flow of chi (vital energy) from the feet, up the spine to the top of the head, and then down the front of the body to the abdomen. To describe this flow of vital energy, the waxing and waning is quite appropriate, for each hexagram in the cycle indicates the progression of the energy to a certain part of the body. Fu (hexagram number 24) represents the very beginning, in which the energy rises from the soles of the feet. Ch’ien (hexagram number 1) represents the point at which the knees are straight and the energy has risen up through the spinal column all the way to the head. K’un (hexagram number 2) represents the outcome of the lowering, in which the energy has moved down to the abdomen.

Ray Wood, 7th Dan Karate, Tai Chi, exponent of Kyushindo Budo