The doctrines of Traditional Chinese Medicine are rooted back 2000 years ago in the books such as the "Huang Ti Nei Jing" (Yellow Emperor's Inner Canon) and the "Shang Han Zha Bing Lun" (Treatise on Cold Damage). It is also based on the cosmological notions like Yin Yang and the Five Elements.
Health of a human being is viewed as harmonious interaction of functional entities with the outside world.
TCM diagnosis consists in tracing symtoms to patterns of an underlying disharmony, mainly by palpating the pulse and inspecting the tongue.