Qi (Ki, Gi)

Qi appears already in the earliest strata of Chinese philosophical writing as the basic stuff of which all things, animate and inanimate, are composed and by which they act; the Huangdi Neijing (Yellow Emperor's Inner Classic), the foundational text of Chinese medicine, treats the free, balanced circulation of qi through the jingluo, the meridian network, as the definition of health, and its obstruction, deficiency or misdirection as the definition of disease. Qi in the body is subdivided by source and function: yuan qi (source qi, inherited from one's parents), gu qi (grain qi, extracted from food), kong qi (air qi, drawn from breath), and derived forms such as wei qi (defensive qi, circulating at the body's surface) and ying qi (nutritive qi, circulating with the blood).

Confucian philosophy from Mencius onward gave qi a moral dimension too, most famously Mencius's haoran zhi qi, "flood-like qi," a vital energy cultivated through righteous conduct rather than breathing technique alone, showing qi was never confined to medicine. The same term and concept, written with the same character, entered Japan as ki and Korea as gi; both retained the Chinese doctrine essentially unchanged, developing their own schools of cultivation and martial application around it rather than a competing definition of what qi itself is.

Qi was among the first Chinese medical concepts to reach Western scholarship in a serious way through Joseph Needham's monumental Science and Civilisation in China, which situated qi within Chinese natural philosophy rather than treating it as folklore, though earlier Jesuit and colonial-era translators had rendered it inconsistently as "breath," "vapor," "air," "ether" or "pneuma," each carrying its own misleading connotations. In the twentieth century qi's fortunes in China itself were politically turbulent: the new Communist government promoted a modernized, secularized qigong and traditional Chinese medicine as scientific national heritage in the 1950s, a process the historian Kim Taylor has documented in detail, stripping much of the older cosmological and religious framing while keeping the meridian physiology intact.

In the West, qi is now most often left untranslated as a loanword, avoiding the older mistranslations, though popular energy-healing literature sometimes conflates it loosely with unrelated Western concepts such as prana or od, an equivalence the traditions themselves do not make. Clinical research on qi-based practices such as acupuncture has produced a large and contested literature; the flow of qi itself, as opposed to the clinical effects of specific interventions, has not been directly measured by any accepted physical method, and is presented here as the tradition describes it rather than as an adjudicated scientific claim.