Yang is expanding, hot, light, and moving Yin is contracting, cold, dark and static. Nature is described as being the result of the interaction of two forces, Yin and Yang, which have four basic characteristics that every Taijiquan (Tai Chi) student should be aware of: Oposition The meaning of the words Yin and Yang were expanded with time to encompass a wider gamut of phenomena, and the words eventually became concepts useful to describe almost everything. The yin side will be more humid, have less life and movement, and be colder than the yang side, which is warmer and has more life and movement in it. This creates a clear difference between the northern yin side of a mountain, which gets less sunlight because of the greater angle of incidence of the light from the sun, and the yang southern side of the mountain, which gets more sunlight. In the northern hemisphere, in latitudes above the Tropic of Cancer, the sun will never be in the zenith, not even in the summer solstice. The writen ideograms Yin (йґ) and Yang (йі) originally refered to the less and more lit sides of a mountain, respectively. This is the origin of the chinese oracle Yi Jing (I Ching), or Book of Changes. There are archeological findings that point to the existence of this idea in chinese prehistoric times: turtle shells were heated on fire, and the resulting cracks would be interpreted to be either weak (вљ‹) or strong (вљЉ), meaning Yin or Yang.

It can be argued that the Yin and Yang concept is the most fundamental idea in Chinese Culture, and also in Taijiquan (Tai Chi).

The yin and yang theory