One night in China, the venerable sage Chang San Fang had a vivid dream of a contest between two creatures, a snake and a crane. The former came up from the earth, and the latter flew down from a tree, and then began a struggle over a morsel of food. The dream recurred, night after night, and yet neither creature was ever wholly victorious. The contest was very evenly matched - an example of opposites in dynamic harmony.

This active engagement of the two principles was given visual form in an ingenious diagram known in Chinese as the Tai Chi Tu. It is a perfect circle, divided into two equal parts by a central, vertical S, which symbolically represents the coiled dragon of Chinese mythology. In the white section, which is associated with the hard, male principle (yang) is a black dot. The latter signifies the presence of the softer feminine, known as yin.

The black region belongs to the yin and has the corresponding white dot representing the male. This overlapping suggests that nothing in the world is wholly yin or yang in itself, but each contains the seed of the other. Also, one may be yang in relation to something, but yin in relation to another. Hence, a grandfather is yang to the grandmother, but perhaps yin to his grandchildren (hopefully).

The incongruent dots, each occupying the sphere of its opposite are a great spur to creative activity; inasmuch as a oyster gives rise to a pearl when a foreign matter enters it, similarly does the trace of the disparate element present in the two fields become the root behind all creative impulse.