ON YIN / YANG
The basic structure of Gung Fu is based on the theory of Yin & Yang, a pair of mutually complementary and interdependent forces that act continuously, without cessation, in this universe. To the Chinese, harmony was regarded as the basic principle of the world order; as a cosmic field of force, in which the Yin and the Yang are eternally complementary and eternally changing. European dualism sees physical and metaphysical as two separate entities, at best as cause and effect, but never paired like sound and echo, or light and shadow, as in the Chinese symbol of all happening; the Yin/Yang.
The above figure shows the symbol of T'ai Chi or, in Cantonese the Tai Kik in which the Yin & Yang are two interlocking parts of one whole, each containing within it's confines the qualities of its complementaries. Etymologically the characters of Yin & Yang mean darkness and light. The ancient character of Yin, the black part of the circle, is a drawing of clouds and hill. Yin can represent anything in the universe as : Negativeness, passiveness, gentleness, internal, insubstantiality, femaleness, moon, darkness, night, etc. The other complementary part of the circle is Yang, the lower part of the character signifies slanting sunrays, while the upper part represents the sun. Yang can represent anything as : positiveness, activeness, firmness, external, substantiality, maleness, sun, brightness, day, etc. The common mistake of the Western World is to identify these two forces, Yin and Yang, as dualistic; that is, Yang being the opposite of Yin, and vice versa. As long as this "oneness" is viewed as two separate entities, realization of the Tao of Gung Fu won't be achieved. In reality things are "whole" and cannot be separated into parts. When I say the heat makes me perspire, the heat and perspiring are just one process as they are co-existent and the one could not exist but for the other. Just as an object needs a subject, the person in question is not taking an independent position but is acting as an assistant. The dualistic philosophy, however, reigned supreme in Europe, dominating the development of Western science. But with the advent of atomic physics, findings based on demonstrable experiment were seen to negate the dualistic theory and the trend of thought since then has led back toward the monistic conception of the ancient Taoist. In atomic physics no distinction is recognized between matter and energy; nor is it possible to make such a distinction, since they are in reality one essence, or at least two poles of the same unit. It is no longer possible, as it was in the mechanistic scientific era, to absolutely define weight, length, or time, etc., as the work of Einstein, Plank, Whitehead and Jeans has demonstrated it is.
In the same way, the Taoist philosophy, against the background of which acupuncture has its origin and developed, is essentially monistic. The Chinese conceived the entire universe as activated by two principles, the Yang and the Yin, the positive and negative, and they considered that nothing that exist, either animate or so-called inanimate, does so, except by virtue of the ceaseless interplay of these two forces. Matter and energy, Yang and Yin, heaven and earth, are conceived of as essentially one or as two co-existent poles of one indivisible whole. Again, it is not possible to make a distinction between matter and energy because they are in reality two poles of the same unit. Things do have their complementaries, and complementaries co-exist and, instead of being mutually exclusive, are in fact mutually exclusive, are in fact mutually dependent and are a function each of the other.
In the Yin/Yang symbol there is a white spot on the black part and a black spot on the white one. This is to illustrate the balance in life, for nothing can survive long by going to either extremes, be it pure Yin (negativeness) or pure Yang ( positiveness). Extreme heat kills as does extreme cold. No violent extremes endure. Nothing last but sober moderation. Notice that the stiffest tree is most easily cracked, while the bamboo or willow survive by bending with the wind. Firmness without pliancy is like a barrel without water, and the pliancy without firmness is like water without a barrel. In Gung Fu, Yang (positiveness) should be concealed in Yin (negativeness) [which is represented symbolically by the white spot on the black part], and Yin (negativeness) in Yang (postiveness) [which is represented symbolically by the black spot on the white part]. A Gung Fu man, then, should be soft - yet not yielding; firm - yet not hard.
When the movement of Yin / Yang flows into extremes, reaction sets in. For when Yang goes to the extreme, it changes back to Yin and vice versa, each being the cause and result of the other. For example, when one works to the extreme, he becomes tired and has to rest (a transition from Yang to Yin). After resting, he can work again (a transition of Yin back to Yang). This incessant changing to Yin/Yang is always continuous.
Therefore, in Gung Fu one should be in harmony with, and not in opposition against, the force of one's opponent. Suppose A applies force on B, B shouldn't oppose or completely give way to it (for these are but the two extreme opposites of B's reaction to A's force). Instead, B should complete A's force with a lesser force (firmness in gentleness) and lead him to the direction of his own movement. This spontaneous assisting of A's movement as he aims it will result in his own defeat. Again, as the butcher preserves his knife by cutting along the barrier of the bone and not against it, a Gung Fu man preserves himself by following the movement of his opponent without opposition.