Yin and yang, the concepts of Chinese philosophy. Originally, yin meant shade and yang meant light. Later, they came to mean cold and warm climates. When ancient thinkers found that all phenomenon has two opposing sides, they adopted yin-yang to explain any two entites in the universe that are opposite.

1. The essential point of yin-yang is inside firmness and outside protection.
2. When the balance between yin and yang is disrupted, it is as if the year had spring without autumn, winter without summer.
3. So, having yin and yang in balance is the best way of preserving life.
4. If yang qi is too st ong to be controlled, yin qi will be drained and lose its force.
5. When yin qi is in a calm and harmonious state and yang qi is in a firm state, the spirit is in the proper state.
6. When yin and yang are separated, the vital qi will be drained as well.
Also learn more in the article Imbalance of Yin and Yang.