Some definitions:   Tai Chi means "the supreme ultimate" and Chuan literally means, "fist" and by extension "martial art" It means improving, and progressing toward the unlimited; it means the immense existence and the great eternal.

Theory:   According to Tai Chi theory, the abilities of the human body are capable of being developed beyond their commonly perceived potential. Civilisation can be improved to the highest levels of achievement. Creativity has no boundaries whatsoever, and the human mind should have no restrictions or barriers placed upon its capabilities.

One reaches the ultimate level, or develops in that direction, by means of the ladder of balanced powers and their natural motions - Yin, the negative power (yielding), and Yang, the positive power (action). From the viewpoint of this theory, it is the interplay of constructive and destructive forces that cause the essence of life to materialise, the material world to manifest. And the spiralling of these forces seems endless.

All of the various directions in which Tai Chi influence was felt were guided by the theory of opposites: the Yin and the Yang, the negative and the positive principle.

For martial purposes   Yin is soft or indirect, while Yang is hard or direct. Soft is not necessarily better than hard or vice versa; it's a matter of using what is appropriate under an existing set of circumstances. For example, we can use softness in the form of evasion and diversion to overcome hardness in the form of attacks, and we can use hardness to overcome softness by attacking the vulnerable points of an assailants body.

Beyond this we need to be able to switch between Yin and Yang with ease. The same theory also governs the health and technical aspects of the art.