Yin Yang

Although everything contains Yin and Yang, these are never present in a static 50: 50 proportion, but in a dynamic and constantly changing balance. For example, the human body's temperature is nearly constant within a very narrow range. This is not the result of a static situation, but of a dynamic balance of many opposing forces.
The main points of this interdependence are:
Four aspects of Yin-Yang relationship
Although Yin and Yang are opposite, they are also interdependent: one cannot exist without the other. Everything contains opposite forces that are mutually exclusive, but, at the same time, depend on each other. Day cannot come but after the night and vice versa; there cannot be activity without rest, energy without matter or contraction without expansion.
The main aspects of the Yin-Yang relationship can be summarized into four:
A passage from chapter 36 of the Daoist classic 'Dao De Jing' by Lao Zi illustrates this point well: 'In order to contract, it is necessary first to expand'. 9
The opposition of Yin and Yang
Yin and Yang are in a constant state of dynamic balance, which is maintained by a continuous adjustment of their relative levels. When either Yin or Yang is out of balance, each necessarily affects the other and by changing their proportion they achieve a new balance.
Yin and Yang are either opposite stages of a cycle or opposite states of aggregation of matter as explained above. Nothing in the natural world escapes this opposition. It is this very inner contradiction that constitutes the motive force of all the changes, development and decay of things.
Besides the normal state of balance of Yin and Yang, there are four possible states of imbalance:
However, the opposition is relative, not absolute, in so far as nothing is totally Yin or totally Yang.