Yin and Yang

Yin Yang is the principle of natural and complementary forces, patterns and things that depend on one another and do not make sense on their own.

These may be masculine and feminine, but they could be darkness and light (which is closer to the original meaning of the dark and light sides of a hill), wet and dry or action and inaction.

These are opposites that fit together seamlessly and work in perfect harmony. You can see this by looking at the yin yang symbol.

The yin yang concept is not the same as Western dualism, because the two opposites are not at war, but in harmony.

This can be seen very clearly in the symbol: the dark area contains a spot of light, and vice versa, and the two opposites are intertwined and bound together within the unifying circle.

Yin and yang are not static, the balance ebbs and flows between them - this is implied in the flowing curve where they meet.

- Taken BBC website Concepts Within Taoism