The basic structure of YIN-YANG CHI (kung- fu martial art) is based on the theory of Yin and Yang, a pair of mutually complementary and interdependent forces that act continuously, without cessation, in this universe. Harmony is regarded as the basic principle of the world order, as a cosmic field of force in which Yin and Yang are eternally complimentary and eternally changing.
The figure shows the symbol of yin and yang are two interlocking parts of one whole, each containing with in its confines the qualities of its complementary etymologically the characters of yin and yang means darkness and light. The ancient character of Yin, the black part of the circle, is drawing of clouds and hill.
Yin can represent anything in the universe.
As: Negative ness, passiveness, gentleness, internal, insubstantiality, femaleness, moon, darkness, night, earth, rest, flat 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 in the universe.
As: positive ness, activeness, firmness, external, substantiality, maleness, sun, brightness, day, heaven, light etc…
In the Yin- Yang symbol there is a white spot on the black part and a black spot on the white part, this is illustrate the balance in life, for nothing can survive long by going to either extremes, be it pure Yin (negative ness) or Yang (positive ness). Extreme heat kills as doe’s extreme cold. No violent extremes endure. Nothing lasts but sober moderation. Notice that the stiffest tree most easily cracked, while the bamboo or willow survive by bending with the wind. Firmness without pliancy is like a barrel without water, and pliancy without firmness is like water without barrel. In kung fu, Yang (positive ness) should be concealed in Yin (negative ness), which is represented symbolically by the white spot on the black part, and Yin (negative ness) in Yang (positive ness) which is represented symbolically by the black spot on the white part. A kung fu man, should be soft – yet not yielding; firm – yet not hard.
When the movement of Yin/Yang flows into extremes, reaction set in. for when Yang goes to the extreme, it changed back to Yin and vice versa, each being the cause and result of the other. For example, when one work to 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 of Yin/Yang is always continuous.
There fore, in kung fu one should be in harmony with, and not in opposition against, the force of once opponent.
Gentleness and firmness (Yin & Yang) are two “interdependent” and “complimentary” forces in the "Yin Yang Chi kung fu", and the aim is the attainment and maintenance of perfect balance between there two forces.
Gentleness/Firmness is one inseparable force of one unceasing interplay of movement. If a person riding a bicycle wishes to go somewhere, for example, he can’t pump on both the pedals at the same time or not pump on them at all. In order to move forward he pumps on one pedal while simultaneously releasing the other. So the movement of going forward requires this “oneness” of pumping and releasing. Pumping then is the result of releasing and vice versa, each being the cause of the other.
The same thing applies to the movement in kung-fu, which is always the ceaseless interplay of the two forces of gentleness and firmness. They are conceived of as essentially one, or two coexistent forces of one indivisible whole. Their meaning (gentleness/firmness) is derived from each other and their completion through each other.
Gentleness alone can’t forever dissolve away great force, nor can sheer brute force forever subdue one’s foe. In order to survive in combat, the harmonious interfusion of gentleness and firmness as a whole is necessary, sometimes one dominating and sometimes the other, in a wave – like succession. The movement then truly flows; for the true fluidity of movement is in its changeability.
Instead of opposing force by force, a kung fu man completes his opponent’s movement by accepting his flow of energy as he aims it, and defeats him by borrowing his own force. This, in Kung – fu is known as the low of adaptation, in order to reconcile one self to the changing movements of the opponent, a kung fu man should first of all understand the true meaning of gentleness and firmness.
There is no dislocation in the way of kung fu movement. They are done with flowing continuity like the movement of rover that is forever flowing without a movement of cessation or standing still. As soon as a movement is approximately finished, it immediately flows into another one without stopping. Thus defense and attack are alternately producing one another.
Firmness and gentleness in the art of kung fu are not isolated, but coalescent, and the same goes for the various movements such as attack and defense, expansion and contraction, pushing and pulling etc...
Therefore one shouldn’t favor too much on either gentleness or firmness alone so that he can truly appreciate the “good/bad” of them. Remember, gentleness versus firmness is not a situation, but gentleness/firmness as oneness in "YIN YANG CHI (kung fu martial art)"