In traditional Chinese culture, qì or ch’i (About this sound qì, also known as ki in Japanese culture) is an active principle forming part of any living thing. Qi literally translates as “breath”, “air”, or “gas”, and figuratively as “material energy”, “life force”, or “energy flow”. Qi is the central underlying principle in traditional Chinese medicine and martial arts.
References to concepts analogous to the qi taken to be the life-process or flow of energy that sustains living beings are found in many belief systems, especially in Asia. Philosophical conceptions of qi from the earliest records of Chinese philosophy (5th century BCE) correspond to Western notions of humours, the ancient Hindu yogic concept of prana (“life force” in Sanskrit) and traditional Jewish sources refer to as the Nefesh level of soul within the body. An early form of the idea comes from the writings of the Chinese philosopher Mencius (4th century BCE). Historically, the Huangdi Neijing/”The Yellow Emperor’s Classic of Medicine” (circa 2nd century BCE) is credited with first establishing the pathways through which qi circulates in the human body.