Five Element theory is one of the major systems of thought within traditional Chinese medicine. The Five Element theory has been used more than 2,000 years as a method of diagnosis and treatment. Essentially, Five Element theory is used to help explain the cause of particular diseases, and to associate signs or symptoms to particular organs and afflictions. In the context of "phases," Five Element theory helps to explain the processes occurring in the body throughout various stages of disease and healing.
From: Wilkinson, R., & Faleiro, R. (2007). Acupuncture in pain management.Continuing Education in Anaesthesia and Critical Care Pain, 7, 135-138. doi:10.1093/bjaceaccp/mkm021