In Chinese philosophy, Yin and Yang are opposite forces that form a whole. Everything contains both yin and yang in a balance that is always changing, such as light and darkness, good and evil, male and female, health and illness and so on. These are two primal opposing but complementary principles or cosmic forces said to be found in all non-static objects and processes in the universe. They are opposing forces that keep the universe in a harmonic balance.
This concept is incorporated into all aspects of life, learn it, understand it and live it in Martial Arts as well as Healing. Here are some books that may be of interest to you if you seek knowledge:
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The Five Element Theory, (wood, fire, earth, metal and water) much like the Yin & Yang, is an ancient philosophy used by the Chinese to explain the intricacies of the physical universe. This theory of five elements is used to interpret the relationship between the human body and the environment. According to the theory, the five elements are interacting constantly, moving and changing their directive energies. This energy is directed toward CREATION (generation) or DESTRUCTION (interaction), and the interdependence of the five elements explains the complexity of the material world as well as the coexistence between the human body and the natural world.
"In traditional Chinese medicine, the visceral organs, as well as other organs and tissues, have similar properties to the five elements; they interact physiologically and pathologically as the five elements do. Through similarity comparison, different phenomena are attributed to the categories of the five elements. Based on the characteristics, forms, and functions of different phenomena, the complex links between physiology and pathology as well as the interconnection between the human body and the natural world are explained. " (http://www.tcmpage.com/five_elements.html)
This table shows the interaction between the 5 five elements, the human body and the natural world: (http://www.tcmpage.com/five_elements.html)
This is just one of many charts designed by the Chinese to explain how the elements interact with the human body. On the diagram above you can see how wood creates or enhances fire, and fire creates or enhances earth, earth creates or enhances metal, metal creates or enhances water and water creates or enhances wood. On the other hand you have wood destroying earth, earth destroying water, water destroying fire, fire destroying metal and metal destroying wood. You must understand that the words create and destroy are not used in the absolute concept of the words when we are talking about the 5 Elements. The concept is to understand that if you have an illnes that is due to too much fire, you may have to use the element of water to heal or decrease the fire. On the other hand, if you have an illness because you are lacking fire, you may need to use wood to create or enhance the fire in order to heal. This is the reason we use multiple charts which may aid us in acquiring the knowledge to heal. There are many books and websites that will help you understand the concepts of the 5 Element Theory. I can only introduce the concept and you may do the reserch.