These can also be related to the selection of food and herbs. Notice the correspondence between the Chinese philosophy and the underlying Indian philosophy, which also classifies everything in the universe under earth, water, fire, air, and ether. Each person's physical and mental constitution can be described as a balance of the elements in which one or more may naturally dominate. The proportion of the elements in a person determines his or her temperament. Oriental medicine considers the ideal condition as one in which all the five elements are in balance or in harmony.
Wood is said to be the mother of fire and the son of water.
Using these relationships one can describe all possible yin-yang imbalances within the body. The thrust of five element diagnosis is to isolate and treat the imbalanced element, because an imbalanced element is like a weak link in your energetic chain that can undermine the strength of your mind, body and spirit.