At some point in your Chinese Medicine education, you'll learn that the herbal formula, Cinnamon Twig Decoction, or Guìzhī Tāng 桂枝湯, is said to have the special ability to "harmonize the ying and wei." Yet, even though this aphorism will be etched into your mind for all of eternity, you may have a difficult time being able to find someone who can provide a clear answer as to what this actually means and why it is useful in clinical practice. To help shed some light on this somewhat enigmatic Chinese aphorism, this article will go over the differences between yíng qì 營氣, often translated as "camp" or "nutritive" qi, and wèi qì 衛氣, often translated as "defensive" qi.
Differentiating ying and wei qi
Ying and wei refer to the two primary umbrella aspects of qi movement in the body that qualify as a yin-yang pair. Both types of qi movement patterns can be differentiated by interoceptive sensation, or the qualitative sensation of how qi can be felt to move in the body. In other words, it was the embodied experience of the movement patterns of qi that informed how these two types of qi were first differentiated. And their differences directly relate to the different ways that qi was thought to regulate internal physiology, as well as how the two came to be thought of as a "yin-yang pair." These concepts were briefly touched upon in the Neijing (more to come on that), but the passages in the Neijing are terse, and difficult to decode without the direct understanding imparted from embodied experience. Thus, the differences between ying and wei are not only theoretical concepts, but sensations that can be directly experienced by those who are able to feel qi.
When it comes to understanding ying and wei, the most important difference is that ying qi circulates within a defined pathway, which includes the pathways of the channels and blood vessels, whereas wei qi does not circulate within a defined pathway. Experientially, ying qi can be felt as qi that circulates around a relatively linearly pathway and "stays within its lane" like water flowing in a river, whereas wei qi moves through the body unrestrained, like mist floating through space.
Ying and wei as a yin-yang pair
Ying qi is said to be yin compared to its counterpart, as ying qi remains relatively enclosed within its space, like the energy of a plant stored in the roots in winter, the most yin time of the year. Wei qi is said to be yang based on the same logic, that it floats out toward the exterior, the movement of qi in summer, the most yang time of the year.
Etymology of ying qi 營氣 (aka camp or nutritive qi)
The character for yíng, 營, has two fire components (火), which were originally two intertwined flowers (Figure 1). Both flowers and fire are correlated to the expansiveness associated with the season of summer. In the Seal Script, instead of two flowers, there is a line connecting the two spaces of 吕 lǔ, which illustrates the interdependent relationship between the channels and vessels, the pathways in which ying qi flows, which are linked together and interact with one another. A disruption in the flow of one of the two will affect the other, as the meridians and blood vessels are a yin-yang pair, just like camp and defensive qi. The roof 宀 over 吕 reinforces the point that camp qi travels within the defined area of the channels and vessels. Roofs are often used in character composition to illustrate the concept of something that takes place in a particular area or space.
So, at this point, one may ask why ying qi has so much yang symbolism if it is the yin counterpart to wei qi. To explain, while ying qi is yin compared to wei qi, both ying and wei both inherently have individual qualities that are an admixture both yin and yang. If these individual qualities are considered in a piecemeal fashion, they function quite like those little dots on the yin-yang symbol----there is always some yin within yang and vice versa. Everything is relative to context. While ying qi is yin compared to wei qi, any kind of accumulated qi (a requirement of being able to feel/perceive the movement patterns and qualities of qi is to have a good quantity of it), will move qi in a yang fashion (up and out). Accumulated qi is what is most often meant by the larger umbrella term of "yang qi"...when qi accumulates to a certain threshhold, it produces the sensation of heat, which is yang.
Etymology of wei qi 衛氣 (aka defensive qi)
The oracle bone version of the character for 衛 wèi shows the crossroads of 行, signifying an energetic movement pattern, with four feet, 夂zhǐ, surrounding the exterior, signifying something that is moving out to the exterior from the interior. The bronze era version shows that a movement happening outside of a defined space, as the feet are located outside of the 口 kǒu component (Figure 2).
Defensive qi moves from the interior toward the exterior, where it mildly accumulates and “guards” the exterior, and thus provides the qi that performs the work of opening and closing the pores of the skin. This process functions similarly in plants where water and gas move up the stem and out through the stomata, the pores in the leaves of the plant, thereby promoting the exchange of water and gases. Qi can also be “breathed” through the pores of the skin, as the Daoists reported. A recent clinical study in humans confirmed this by showing that oxygen intake through the skin contributes in a measurable way to overall oxygen supply (Stücker et al., 2002).
In Chinese medicine, deficiency of defensive qi results in insufficient qi at the surface of the body, leading to an inability to control the pores, thus resulting in spontaneous sweating and a pathological loss of internal qi and fluids out through the surface. Thus, the Shānghán Lùn formula, Guì zhī tāng (桂枝湯), which is indicated for wind strike (風中) harmonizes the camp and defensive qi. The formula does this through qi dynamics by mimicking the natural action of defensive qi—by moving qi from the interior toward the exterior, thus mirroring the way the qi moves in summer (Tàiyáng)—doing this reinstates the function of the pores. Similar to bland herbs, defensive qi is experienced as a movement that passes through the body without impediment, but different in that bland herbs move down whereas defensive qi moves up.
Ying and wei in the Neijing
Sùwèn 43 illustrates the difference between camp and defensive qi:
營者水穀之精氣也。和調於五藏，灑陳於六府，乃能入於脈也。故循脈上下，貫五藏絡六府也。
Camp [qi] is the clear qi of water [and] grains [digested food]. [Once the] five zàng are harmoniously regulated, [and the qi] has washed over the terrain of the fǔ organs, only then can it enter circulation. Thus it follows circulation, rising and descending, linking the five zàng and connecting the six fǔ organs.
衛者水穀之悍氣也。其氣慓疾滑利。不能入於脈也。
Defensive [qi] is the yang qi of water [and] grains. Its qi disperses illness by sliding and cutting through. It cannot enter into circulation.
悍 hàn, for which the literal meaning is “fierce or brave,” is translated as “yang” here, as the character contains the components of a heart (忄) with the sun (日) shining over a flowering sprout (干), all yang correspondences relating to the season of summer (Figure 3). Again, the action of defensive qi is yang in the way it expands out through the body’s exterior, compared to the action of camp qi, which is yin in the way it remains confined to the interior space of the channels and vessels.
Clinical implications for treating wind with herbal medicine
Wind has a pathological influence on camp and defensive qi, as the erratic movement of wind pushes camp qi from its home within the channels and vessels out into the general space of the body, where it essentially becomes defensive qi and is lost through movement out through the pores. In this process, the channels and vessels become deficient, and qi accumulates at the surface, causing muscle tension and inflammation from qi stagnation at the exterior. Thus, wind leads to simultaneous deficiency and stagnation of qi in the channels and vessels, which over time leads to blood deficiency and stagnation due to the intimate relationship of blood and qi. The rapid devolution into a condition of combined excess and deficiency can cause significant deleterious effects for the health of a person with internal wind if left untreated.
Wind requires a gathering strategy so that qi can gravitate back to its encampment within the blood vessels and channels, instead of wandering around in other places causing destruction, as an errant dopplegänger of defensive qi. This gathering can be accomplished with sour or sweet herbs, with relative proportions depending on the severity of stagnation. When wind has been present for a long time, there is a high likelihood of significant stagnation, as both qi and blood become deficient. With conditions that have significant stagnation, it becomes necessary to limit or artfully moderate sour herbs, which can strongly exacerbate stagnation. To enhance the gathering quality of sour herbs, sweet herbs can be used to moderate the wind qi in a way that is more harmonious. To the same end, depending on whether the condition is presenting as more hot or cold, tailoring the formula to moderate the condition using warm or cool herbs will balance the dominant thermal expression of the patient.
References
Stücker, M., Struk, A., Altmeyer, P., Herde, M., Baumgärtl, H., & Lübbers, D. W. (2002). The cutaneous uptake of atmospheric oxygen contributes significantly to the oxygen supply of human dermis and epidermis. The Journal of Physiology, 538(3), 985–994. https://doi.org/10.1113/jphysiol.2001.013067
The pictograph images of the older Chinese characters are from Richard Sears' work at Chinese Etymology. Please consider donating to help support his research.
Citation
Juniper, Evren. “Ying and Wei Qi (營衛氣) in East Asian Medicine.” Universal Qi, 2022, https://www.universalqi.org/post/ying-and-wei.
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