What Is Qiheng? Abnormality Must Be Defined from a Model of Normality

“Qiheng” opens with one of the most methodologically important definitions in the whole work:

Qi is what does not follow the constant of Kuidu; Heng is what proceeds according to the way of Kuidu. Qiheng and Kuidu share one Dao.

“Qi” and “Heng” are not two opposed medical systems. They are deviation and baseline within the same system of measurement.

Without Heng, there is no way to define Qi

Why did the preceding dozens of articles spend so much effort defining one breath of a normal person, sixty fen, Huangzhong, Hou-She, and divisions of oscillation?

Because without a normal reference one can only say that a pulse is “strange,” “weak,” or “fast,” without knowing how far it deviates or on which dimension the deviation occurs.

“Qiheng” therefore says to compare by category with the measure of normal-person breath and movement, then examine the coming-going, high-low, long-short, and entry-exit of qi.

Abnormality is not one threshold crossing

The Mirror Classic later observes simultaneously:

• from which Hou movement begins;
• to which Hou it travels;
• whether oscillation is three, six, or nine fen;
• the magnitude and sharpness-width of the surge;
• whether breathing entry and exit correspond;
• whether the tone and lü being reached are in proper position.

“Qi” is therefore a multidimensional deviation, not merely an abnormal heart rate or a single pulse position.

“The Dao is one” puts normal and abnormal back into one coordinate system

The phrase “Qiheng and Kuidu, the Dao lies in one” is especially important. It means normality and abnormality must be measured by the same rules.

If normal physiology uses one standard while disease is described through an entirely separate set of mysterious labels, real comparison becomes impossible.

The Mirror Classic’s diagnostic direction is therefore closer to: first establish one coordinate system, then observe the direction and magnitude by which an individual leaves the baseline.

This also leaves room for the final six individualized baselines

At the end of the work we are told that four pulse movements in one breath can be normal for some people, while six can be normal for others. Heng therefore cannot mean only a population-wide average. It must also incorporate individual type and seasonal-temporal background.

The next article first examines how “Qiheng” reinterprets the three Cun of the Qi Mouth as three sources: Heaven, Earth, and the roots of life.