Wuxing are the five elements: metal, wood, water, fire, earth. Ancient Chinese thinkers used the five elements to explain the origin of all things in the universe and the unity of diversification.

1. Qi Bo said, yin, which contains vital qi within, is the source of qi in the human body.
2. If yin cannot overpower yang, the pulse will be quick. Yang protects the outside body and strengthens muscles and skin.
3. The horse bears the characteristics of yang. If yang becomes excessively strong, it will run out of control. 
4. If yang qi cannot overpower yin, the qi within the five internal organs will be in disorder and the nine orifices will be blocked.
5. So a sage knows how to balance yin and yang and keep them in their proper places. In this way, tendons and pulse are in harmony, bones and marrow are strong, qi and blood circulate normally.
6. When the body is in balance, evil qi will not be able to invade.
7. You will have sharp ears and eyes and vital qi will stand erect, not shaken by evil qi.
Also learn more in the article Five Elements Implication.