Qi (Chinese principle)
Qi (spelled in Mandarin Pinyin romanization), pronounced Template:IPA2, also ch'i (in Wade-Giles romanization) or ki (in Japanese romanization), is a fundamental concept of traditional Chinese culture. Qi is believed to be part of every living thing that exists, as a kind of "life force" or "spiritual energy". It is frequently translated as "energy flow", or literally as "air" or "breath". (For example, "tianqi", literally "sky breath", is the ordinary Chinese word for "weather"). In Mandarin Chinese it is pronounced something like "chee" in English, but the tongue position is different.  (See Media:Difficult Sounds.GIF.)

# Etymology
The etymological explanation for the form of the qi logogram in the traditional form  is steam () rising from rice () as it cooks.
The earliest way of writing qi consisted of three wavy lines, used to represent one's breath seen on a cold day. A later version, , (identical to the present-day simplified character) is a stylized version of those same three lines. For some reason, early writers of Chinese found it desirable to substitute for  a cognate, character that originally meant to feed other people in a social context such as providing food for guests. Appropriately, that character combined the three-line qi character with the character for the grain we call rice. So  plus  formed , and that is the traditional character still used today. (See the Oracle bone character, the Seal script character and the modern "school standard" or Kai shu characters in the box at the right for three stages of the evolution of this character.)
References to things analogous to the qi taken to be the life-process or flow of metaphysical energy that sustains living beings are found in many belief systems, especially in Asia. Philosophical conceptions of qi date from the earliest recorded times in Chinese thinking. One of the important early cultural heroes in Chinese mythology is Huang Di (the Yellow Emperor). He is identified in the legends of China as the one who first collected and formalized much of what subsequently became known as traditional Chinese medicine.
The earliest extant book that speaks of qi is the Analects of Confucius (composed from the notes of individual students some time after his death in 479 B.C.) Unlike the legendary accounts mentioned above, the Analects has a clear date in history, and most later books (at least the ones that do not purport to be relics of the legendary earliest rulers) can also be assigned clear dates in history.
Although the concept of qi has been very important within many Chinese philosophies, over the centuries their descriptions of qi have been varied and may seem to be in conflict with each other. Understanding of these disputes is complicated for people who did not grow up using the Chinese concept and its associated concepts. Until China came into contact with Western scientific and philosophical ideas (primarily by way of Catholic missionaries), they knew about things like stones and lightning, but they would not have categorized them in terms of matter and energy. Qi and li (, li, pattern) are their fundamental categories much as matter and energy have been fundamental categories for people in the West. Their use of qi (lifebreath) and li (pattern, regularity, form, order) as their primary categories leaves in question how to account for liquids and solids, and, once the Western idea of energy came on the scene, how to relate it to the native idea of "qi". If Chinese and Western concepts are mixed in an attempt to characterize some of the problems that arise with the Chinese conceptual system, then one might ask whether qi exists as a "force" separate from "matter", whether qi arises from "matter", or whether "matter" arises from qi. But those questions occur only in the hybrid conceptual system.
Analysis of the relationship between qi (breath, lifebreath) and li (the patterns, regularities, or the formal aspect of things) has been very difficult for Chinese philosophers. In addition, how to account for what people in the West might casually categorize as "solid stuff" was also a problem. Fairly early on, some Chinese thinkers began to believe that there are different fractions of qi (in the sense that different fractions can be extracted from crude oil in a catalytic cracker), and that the coarsest and heaviest fractions of qi form solid things such as rocks, the earth, etc., whereas lighter fractions form liquids, and the most ethereal fractions are the "lifebreath" that animates living beings.

# Qi in early philosophical texts
The earliest texts that speak of qi give some indications of how the concept developed. The philosopher Mo Di (also known as Mo Zi or "Master Mo") used the word qi to refer to noxious vapors that would in due time arise from a corpse were it not buried at a sufficient depth. He reported that early civilized humans learned how to live in houses to protect their qi from the moisture that had troubled them when they lived in caves. He also associated maintaining one's qi with providing oneself adequate nutrition. And, in regard to another kind of qi he recorded how some people performed a kind of prognostication by observing the qi (clouds) in the sky.
In the "Analects of Confucius", (composed from the notes of individual students sometime after his death in 479 B.C.), "qi" can mean "breath", and it can be combined with the Chinese word for blood (making , xue-qi, blood and breath) and that concept can be used to account for motivational characteristics. The Analects, 16:7, says:
The  noble man guards himself against three things. When he is young, his xue-qi has not yet stabilized, so he guards himself against sexual passion.  When he reaches his prime, his xue-qi is not easily subdued, so he guards himself against combativeness. When he reaches old age, his xue-qi is already depleted, so he guards himself against acquisitiveness.
Meng Ke (also known as Meng Zi, Master Meng, or Mencius) described a kind of qi that might be characterized as an individual's vital energies. This qi was necessary to activity, and it could be controlled by a well-integrated will power. But this qi could not adequately be characterized by English words like "lifebreath" or "bio-plasma" because when properly nurtured it was capable of extending beyond the human body to reach throughout the universe. This qi can be augmented by means of careful exercise of one's moral capacities. On the other hand, the qi of an individual can be degraded by averse external forces that succeed in operating on that individual.
Not only human beings and animals were believed to have "qi".  Zhuang Zhou (also known as Zhuang Zi or Master Zhuang) indicated that wind is the "qi" of the earth. Moreover, cosmic Yin and Yang "are the greatest of 'qi'." He describes qi as "issuing forth" and creating profound effects.
Zhuang Zi gave us one of the most productive of insights into the nature of "qi". He said "Human beings are born  the accumulation of 'qi'. When it accumulates there is life. When it dissipates there is death.... There is one 'qi' that connects and pervades everything in the world."
Another passage traces life to intercourse between Heaven and Earth: "The highest Yin is the most restrained. The highest Yang is the most exuberant. The restrained comes forth from Heaven. The exuberant issues forth from Earth. The two intertwine and penetrate forming a harmony, and  things are born."
Zhuang Zi was a contemporary of Mencius. Xun Zi followed them after some years. At 9:69/127, Xun Zi says: "Fire and water have qi but do not have life. Grasses and trees have life but do not have perceptivity. Fowl and beasts have perceptivity but do not have yi (sense of right and wrong, duty, justice). Men have qi, life, perceptivity, and yi." This passage gives us some insight into his idea of "qi". Chinese people at such an early time had no concept of radiant energy. But they were aware that one can be heated by a campfire even though the air between camper and fire is quite cold. Clearly, something is emitted by the fire and reaches the camper. They called it "qi". At 18:62/122, he too uses "qi" to refer to the vital forces of the body that decline with advanced age.
Later, the syncretic text assembled under the direction of Liu An, the Huai Nan Zi has a passage that presages most of what is given greater detail by the Neo-Confucians:
Heaven (seen here as the ultimate source of all being) falls (duo , i.e., descends into proto-immanence) as the formless. Fleeting, fluttering, penetrating, amorphous it is, and so it is called the Supreme Luminary. The dao begins in the Void Brightening. The Void Brightening produces the universe (yu-zhou ). The universe produces qi. Qi has bounds. The clear, yang  was ethereal and so formed heaven. The heavy, turbid  was congealed and impeded and so formed earth. The conjunction of the clear, yang  was fluid and easy. The conjunction of the heavy, turbid  was strained and difficult. So heaven was formed first and earth was made fast later. The pervading essence (xi-jing) of heaven and earth becomes yin and yang. The concentrated (zhuan) essences of yin and yang become the four seasons. The dispersed (san) essences of the four seasons become the myriad creatures. The hot qi of yang in accumulating produces fire. The essence (jing) of the fire-qi becomes the sun. The cold qi of yin in accumulating produces water. The essence of the water-qi becomes the moon. The essences produced by coitus (yin) of the sun and moon become the stars and celestial markpoints (chen, planets).
The development of the ideas of qi and of qi zhi zhi xing () in Neo-Confucianism go beyond the scope of a fundamental account of Chinese ideas about qi, but the fundamentals are contained in the above passage.

# Qi in traditional Chinese medicine
Theories of traditional Chinese medicine assert that the body has natural patterns of qi that circulate in channels called meridians in English. Symptoms of various illnesses are often believed to be the product of disrupted, blocked, or unbalanced qi movement (interrupted flow) through the body's meridians, as well as deficiencies or imbalances of qi (homeostatic imbalance) in the various Zang Fu organs. Traditional Chinese medicine often seeks to relieve these imbalances by adjusting the circulation of qi (metabolic energy flow) in the body using a variety of therapeutic techniques. Some of these techniques include herbal medicines, special diets, physical training regimens (Qigong, Tai Chi Chuan, and martial arts training), moxibustion, massage to clear blockages, and acupuncture, which uses small diameter metal needles inserted into the skin and underlying tissues to reroute or balance qi.

# Qi in Feng Shui
The traditional Chinese art of placement and arrangement of space called Feng Shui is based on the flow of qi, interactions between the five elements, yin and yang and other factors. The retention or dissipation of qi is believed to affect the health, wealth, energy level, luck and many other aspects of the occupants of the space.  Color, shape and the physical location of each item in a space affects the flow of qi by slowing it down, redirecting it or accelerating it, which directly affects the energy level of the occupants.

# Nature of qi
Disputing the nature of qi is an old pursuit in Chinese philosophy.  Among some traditional Chinese medicine practitioners, qi is sometimes thought of as a metaphor for biological processes similar to the Western concept of energy flow for homeostatic balance in biological regulations.  Attempts to directly connect qi with some scientific phenomena have been made since the mid-nineteenth century. The philosopher Kang Youwei believed that qi was synonymous with the later-abandoned concept of luminiferous ether.
Views of qi as an esoteric "force" tend to be more prominent in the West, where it has sometimes been associated with New Age spiritualism. These views are less prominent in modern communist China, where traditional Chinese medicine is often practiced and considered effective, but in which esoteric notions of qi are considered to contradict the secular nature of Marxist dialectic materialism. China's current government in fact formally embraces anti-spiritual atheism.  Many traditional martial arts schools also eschew a supernatural approach to the issue, identifying "external qi" or "internal qi" as representative of the varying leverage principles used to improve the efficacy of a well-trained, healthier than normal body with a given work load.
Some complementary and alternative medicine approaches not only assume the existence of qi but believe that the purported subtle energy running through and surrounding the body can be manipulated so as to cultivate increased physical, psychological and spiritual health. Acupuncture, along with other practices of TCM, ayurveda, and many other traditional disciplines worldwide provide examples of similar beliefs.

## Scientific investigation
Modern science rejects the concept of "qi", but has considered explanations within known biological science. It has been hypothesized that the therapeutic effects of acupuncture can be explained by changes in nerve cells, to endorphin-release, to relaxation or by simple placebo effects. The NIH Consensus Statement on acupuncture in 1997 noted that concepts such as Qi "are difficult to reconcile with contemporary biomedical information but continue to play an important role in the evaluation of patients and the formulation of treatment in acupuncture."
It is hypothesized that qi could be transmitted through the fascia independent of any neurological activity.

# Interpretation in Japan and Korea
In the Japanese language, the Chinese character corresponding to qi () is pronounced ki.  The Japanese language contains over 11,442 known usages of "ki" as a compound. As a compound, it may represent syllables associated with the mind, the heart, feeling, the atmosphere, and flavor.
We see parallel development in Korean language usage as Koreans have long used Chinese characters (hanja) along side the indigenous Korean system (hangul). There are also some cases in which commonalities are due to the long history of their geographical relationship.
The character for "ki" in hangul is "", which is pronounced as 'gi' with a hard g.
Japanese usages of note also include tenki (weather ), genki (healthy, doing fine ), byouki (sick, sickness ) and kiai (spirit shout  ).
Korean compound usages of ki are also comparable including gibun (feeling, sensation ) and gihap (spirit shout ).

# Qi in martial arts
Qi is a central concept in many Chinese, Korean and Japanese martial arts. While a traditional Neo-Confucian explanation of the principle is given in most martial art schools, many New Age-oriented or neo-ninja schools approach the subject from a more syncretist point of view, especially in the west.
The spiritual concept analogous to Chinese ki appears in the martial arts, such as Japanese aikido (See Ki Society). The Korean system of hapkido, although a different martial art, shares the same characters as pre World War II aikido (). The character for 'ki' remained the same until 1946 when the character for ki was simplified in Japan. In hangul, the indigenous Korean system, hapkido would be rendered ''.
The concept of aiki as occurring when the character ai (), representing harmony, together, or joining is combined with the character for ki and is often interpreted representing a combining, blending or coordinating of energy or a principle of non-contention of forces.
Most systems which incorporate the idea of ki believe that a practitioner may harness the energy stored in a special point in the lower stomach referred to as tan t'ien () in Chinese, tan den () in Japanese, tan jon ( or ) in Korean and dan tian () in Thai, and utilize this energy in their martial technique, usually by employing special breathing techniques also found in the Buddhistic meditation practises common to these countries.
Most long term or professional martial arts practitioners report that the practice of building qi via breathing exercises, deep relaxation and meditation practices causes profound physiological changes that enable special martial arts skills. After sufficient practice an ability to feel the qi develops. Sensations such as tingling, warmth and heaviness of the limbs are common. With continued practice the martial artist is able to gradually gain control of these sensations and invoke them at will. In T'ai Chi, for example, one goal is to "sink" or accumulate the qi to the navel area, experienced as a strong sensation of warmth and heaviness, similar to the sensation one feels when an elevator stops. After that, the ability to "circulate" the qi develops, where the martial artist feel warm waves of qi energy moving through the body in harmony with the graceful T'ai Chi movements. Practitioners able to experience these sensations find their sense of touch is enhanced, along with dramatically improved balance and coordination. These skills then enable improved martial arts performance.

# Types of qi
- Yuan qi - (primary qi)
- Jing (TCM) - (nutrient qi)
- Zhong Qi - (pectoral qi)
- Wei Qi - (defensive qi)
- Qigong - (qi cultivation)

# Similar concepts in other cultures
The concept of a life-energy inherent in all living beings seems to be a fairly universal archetype, and appears in numerous ancient religions and systems of metaphysics (in addition to having been borrowed by George Lucas's Star Wars films with the concept of The Force).
Analogies concepts from other cultures include:
- Polynesian mythology: mana
- Australian Aboriginal mythology: maban
- Egyptian mythology : ka
- Finnish mythology: sisu
- Turkish mythology: can
- Greek mythology/Christianity: psykhe
- Roman mythology/Christianity: spiritus
- Roman mythology: numen
- Hebrew mythology: nefesh
- Inuit mythology: inua, sila
- Leni Lenape mythology: manetuwak
- Norse mythology: hugr
- Druidry: Awen
- Yoruba mythology: ashe
- Ghedee practice: mbec
Also related are the philosophical concepts of:
- European alchemy and philosophy: aether, (or ether), quintessence
- Hindu philosophy: prana
Related martial arts and exercise practices include
- Indian culture: Yoga