"One yin, one yang, that is the Tao."
Chapter 5, Hsi-tz'u (part of the Ta Chuan) of the I Ching
The quotation above is the first known reference to yin and yang, the pair of polar energies whose cyclic fluctuations and
interactions cause and govern Creation. Together they are the complementary expressions of the supreme ultimate, t'ai-chi,
the eternal Tao. Yin originally was the name given to the colder, north-facing slope of a mountain, and yang to the warmer,
southern, sun-facing one. Thus yin corresponds to the dark, the receptive, the passive, the feminine; while yang corresponds
to the bright, the creative, the active, the masculine. Yin is the moon, water and the earth. Yang is the sun, fire and the
The mutual fluctuations of these primal energies can be represented by the trigrams
of the I Ching and by the famous symbol shown above. The yin-yang is a dynamic figure, showing the continual interaction
and balance of the two energies, and as such it is a very harmonizing symbol. As each of the energies reaches its apogee, it
begins to transform into its opposite, and this is shown by the dots in the symbol, each located at the fullest point of its
polar force. The culmination of yang contains the seed of yin, just as yin contains the seed of yang.
Lao-tzu in the Tao-te ching wrote:
"Everything has both yin and yang in it - and from their rise-and-fall coupling comes new life."