What is qi?

Qi is the hardest word in Chinese medicine to translate and the easiest to overtranslate. Energy is the usual English, and it is wrong in the way that matters: it makes qi sound like a thing, a fluid or a current you could measure or believe in, and then the whole tradition stands or falls on whether the thing exists. It does not have to. The word names what a body is doing, not a stuff it contains. When the tradition says a person’s qi is low, it means the jobs are not being done: food is not becoming strength, the hands are not warm, colds are caught and kept, things sag that should hold, and nothing moves as it should.

That is the honest version, and it is also the classical one. The character is a picture of vapour. The Lingshu’s nearest thing to a definition is a picture of mist. Two thousand years of physicians used the word the way a cook uses the word heat, as the name of what the fire is doing to the pot, and they built a careful working system on that use. You are not being asked to believe in a substance. You are being asked to notice a difference you have already noticed.

The oldest dictionary in the language, the Shuowen Jiezi of about 100 CE, gives the character in three words and a note. It is the qi of clouds, and it is a drawing. The later form, 氣, sets that vapour over the sign for rice: the steam off a cooking pot, which is where the tradition will locate it in the body as well.

The Suwen makes it the stuff of a person in one sentence, and the sentence is not about medicine. Heaven and earth join their qi, and what results is called a human being. The word does the same work there that it does in a weather report: it names what is happening, and what happens is us.

Asked to define qi, the Lingshu gives a picture. The upper burner, the chest, opens and spreads the flavour of the grain that was eaten, and the spreading steams the skin, fills the body and moistens the hair, like mist and dew watering a field. Read that slowly and the whole idea is in it: qi is what food becomes when a warm body has finished with it, and it is known by what it does to the surface.

And asked what goes wrong, the Suwen answers that a hundred illnesses arise from qi, and then lists nine things that move it the wrong way, of which seven are feelings. Anger sends it up, joy slackens it, grief consumes it, fear sends it down, cold gathers it in, heat lets it out, fright scatters it, overwork wears it, and thought knots it. That list is the tradition’s theory of how the day gets into the body.

The classics sort qi by where it comes from and what it does. Four kinds are enough for a reader; the Lingshu’s eighteenth and seventy-first chapters and the Nanjing give the sources.

Modern textbooks tidy the classics into five functions, and the list is theirs rather than the Neijing’s, but it is a fair summary of what the old physicians watched for. Qi moves: the blood, the breath, the bowel, the thoughts. It warms: the hands, the feet, the belly, the food in it. It defends: the surface against wind and cold. It holds: the blood in the vessels, the organs in place, the sweat in, the urine in. And it makes: food into blood and flesh, drink into fluid, breath into voice. A person whose qi is low fails at those in roughly that order, which is why the tired person is next cold, then always ill, then sagging, and last of all unable to make anything of what they eat.

The tradition’s qi foods are the plain, warm, building ones, and they are given for the tired picture, not the hot one.

• Ginseng 人参, the root the Shennong Bencao Jing puts first: a few slices simmered, in winter, for the person who is truly spent. Not for the hot, the young, or the well.
• Astragalus 黄芪, simmered in a soup, for the person who catches everything: the defensive kind is its business.
• Jujube 大枣, three in a pot of water, for the ordinary tired and for the evening.
• Licorice 甘草, a single slice in the pot, the harmoniser the old formulas end with. A little.
• Warm, cooked, regular, and not too much. The Four Gentlemen, 四君子汤, the physicians’ oldest qi formula, is a physician’s formula and not a recipe; the kitchen version of it is a hot breakfast eaten sitting down.

None of that is a promise, and we make none. It is the floor.

Four finger-widths below the kneecap, a thumb’s width outside the shin bone, is Zusanli, Stomach 36, 足三里, the point the tradition gives to the making of qi from food. Thumb pressure, a minute each side, after meals. It is not a needle and it is not a claim about outcomes.