Yang is always sufficient and yin is always insufficient is a theory of Zhu Danxi, who is a famous person of Yuan dynasty. In Zhu Danxi’s theory, yang stands for essence and blood, and yin stands for energy and fire. That means deficient fire caused of the insufficiency of essence and blood. Zhu Danxi considered that essence and blood is the material basis of people’s life. It consumed time by time, and it is difficult to restore when is damaged. So in this opinion, yin is always insufficient.
If people do not take care of their essence and blood, drink too much and make love too frequently, then their yang energy will turn stronger and difficient fire will have bad influnce on the body. In this condition, many diseases will become serious.
Zhu Danxi founded the method of treating yin deficiency. This method is based on the teory above: takeing good care of your essence and blood is the best way to keep the balance of yin and yang of human body.
