the Yin-Yang symbol or Taijitu, with black representing yin and white representing yang. It is a symbol that reflects the inescapably intertwined duality of all things in nature, a common theme in Taoism. No quality is independent of its opposite, nor so pure that it does not contain its opposite in a diminished form: these concepts are depicted by the vague division between black and white, the flowing boundary between the two, and the smaller circles within the large regions.

Yin and yang consume and support each other.
Yin and yang are usually held in balance as one increases, the other decreases. However, imbalances can occur. There are four possible imbalances: Excess yin, excess yang, yin deficiency, and yang deficiency. During the switch to Daylight saving time, for example, there is more ‘yin’ than ‘yang’. They can again be seen as a pair: by excess of yin there is a yang deficiency and vice versa. The imbalance is also a relative factor: the excess of yang “forces” yin to be more “concentrated”.