Classic Chinese philosophy believes that the primary state of the universe is Qi. Through its constant movement, it produces all the things in the universe, including life. Chinese cultural and medical thought considers it to be as fundamental as Yin and Yang. Thus people in ancient China thought that its accumulation would produce life whereas its dispersion would put an end to life. Its nature is very active and in constant motion whilst also being extremely fine and invisible.
In the theory of TCM, it is the most essential substance that makes up the body and maintains life activities. All vital substances, organs and meridians in the body are formed by the motion, transformation and accumulation of qi.
As an important and unique concept of TCM it is defined and sub-categorised into different types according to its function within the body. This includes: Nutrient (Ying), Defensive (Wei), Primordial (Yuan) and Pectoral (Zong). Each of the body’s Zang-Fu organs and their associated meridians also have their own Qi. Disharmony within the body, organs and/or meridians will lead to either Qi Deficiency (Xu), Stangation (Zhi) or Rebellion (Ni).