TCM is based on the philosophical concept that the human body is a small universe with a set of complete and sophisticated closely-related sub-systems. Those systems usually work balancely and harmoniously to maintain the normal function of the human body. There are also systems (much like the immune system in modern concept) in human body to heal illness automatically. In case of any imbalance between those sub systems in human body, the healing system may lose power and the illness occurs. On the other hand, if balance is restored, the person heals.