Qi in Chinese Medicine
(Part 1 of 2)
Marty Eisen, Ph.D. and Kevin W Chen, Ph.D.
1. What Is Qi?
Before any scientific investigation of Qi, the concept of Qi and its properties in Chinese philosophy must be known, in order to judge how closely any modern scientific interpretation fits.
Qi is a fundamental concept or terminology in traditional Chinese medicine (TCM) with multiple levels of meanings. If you read enough in TCM, you would find that TCM seems to use “qi” to describe almost all invisible forces that affect human lives and health. More specifically, Qi can describe the invisible forces both outside and inside the human body in many different ways (1). We will introduce some of these uses here as we lay out some basic background of Qi in Chinese philosophy and culture.
Qi might have been first discussed by Chinese philosophers (2). Huai Nan Zi, a Daoist book around 122 B.C., states that the Dao originated from Emptiness and Emptiness produced the universe. The universe produced Qi. Here it was most likely referred to qi energy outside of body.
Zhang Zai (1020-1077) said that the Great Void consists of Qi. Qi condenses to become the myriad of things. He clearly understood the concept of the matter-energy continuum, in the sense of modern physics, even though these ideas were conceived centuries later. He also saw the indestructibility of matter-energy as revealed by his statement “Qi in dispersion is substance and so is it in condensation.” “Qi forms myriads of things” implies that Qi must also involve information, in modern terminology. He also said that every birth is a condensation and every death a dispersal of Qi. Thus, just as “Qi” is the energetic foundation of the universe, it is also the physical and spiritual substratum of human life. Zhu Xi (1131-1200) confirmed that Qi condensing can form beings and the conservation of energy, when he stated: “When dispersing, Qi makes the Great Void, only regaining its original misty feature, but not perishing; when condensing it becomes the origin of all beings.”
From these classic discussions (and the recent research findings to be presented later), we should say that a modern scientific explanation of Qi must involve aspects of matter, energy, and information, which remind us of the new finding in modern physics, the “hidden dimensions.”
This universal Qi, postulated by Chinese philosophers, will be denoted by “Qi” to differentiate from its usage in Chinese medicine, which will be denoted by Qi (without quotation). TCM has been using concept of Qi primarily in two senses. The first use is in abbreviation of functions or conditions that nothing else can explain well. Qi is used to describe the complex of functional activities of any organ. For example, Heart-Qi is not a refined substance in the Heart, but indicates the complex of the Heart’s functional activities, such as governing the Blood, controlling the Blood vessels, etc. Thus, there is Liver-Qi, Heart-Qi, Lung-Qi, etc. In a sense, it is also used to indicate disorders of the organ’s function or body’s disorder – for example, “Qi Bi” (Qi constipation) and “Qi Liu” (Qi tumor). These abbreviations will not be discussed in more details here, but Qi as an actual refined substance will.
The second use of Qi is vital energy, which stems from the Chinese character for Qi (氣). Qi can be decomposed into two radicals, which stand for “vapor, steam or gas” and (uncooked) “rice” or grain. In the second case, it is the energy or life-resource within the grain that is called “qi”, not the material or chemical part itself. This is evidence by the fact that rice could lose its taste and “gain qi” after being offered as oblation to the soul. This usage implies that Qi can be used as immaterial as vapor and as dense and material as rice. It also implies that Qi could be just subtle substance (vapor) produced from a coarse one (rice), just as cooking rice produces steam. Thus, sinologists generally agree that Qi is matter-energy in the sense of modern physics.
Natural energies, which are not tangible or visible are particular specializations of this use of “Qi” – for example, Seasonal Qi, Heavely Qi , Earthly Qi and Food Qi. Other examples are environmental factors or forces that may affect human health, such as cold, dampness, dryness, etc.
Just as “Qi” is the energetic foundation of the universe, it is also the physical and spiritual substratum of human life. In Chinese medicine, the terminology employed depends on the state of the energy-matter. Energetic material, ranging from less dense to denser, is termed: Spirit (Shen 神), Energy (Qi 氣), Essence (Jing 精), Blood (Xue 血), Body Fluids (Jin Ye 津液), Marrow (Sui 髓), and Bone (Gu 骨).
The three most important energetic substances for the function of the body are Jing, Qi and Shen, representing different stages or phases of life phenomenon. These are known as the “Three Treasures” or “San Bao”（三宝）.
In order to understand the concept of Qi, we need briefly discuss another related TCM concept “Jing”. Jing is usually translated as “Essence”. The Chinese character implies that it is a refined substance derived from a coarser one. In many senses, Jing could be the internal sources or structure base of Qi. Jing itself can be divided into different types or be looked from different angles. If Qi is used in the sense of function, Jing would be understood as the physiological structure. If Qi is considered as vital energy, then Jing would be the physiological systems that support the energy. For example, endocrine system is frequently referred as “jing” in TCM. Keep it in mind that there are disagreements on what can be called Jing, what can not. Basically there are three different types of Jing discussed in TCM classic books.
Prenatal Jing (Pre-Heaven Essence)
At conception, the Prenatal Jing passes from the parents to the embryo. This essence, together with nourishment derived from the Kidneys of the mother, nourishes the embryo and fetus during pregnancy. It is the only kind of essence present in the fetus.
Prenatal Jing determines basic constitution, strength, vitality, and so individual uniqueness. Since Prenatal Jing is inherited from the parents, it is very difficult to influence in later life. Some say the quality and quantity of Prenatal Jing cannot be altered. The way to conserve Prenatal Jing is by striving for balance in all life activities – moderation in diet, work/rest, and sexual activity. Irregularity or excess in these areas wastes Prenatal Jing. Certain exercises help conserve Prenatal Jing, such as Tai Chi and Qigong. Tortoise breathing may also positively influence it.
Postnatal Jing (Post-Heaven Essence)
After birth, the infant starts to eat, drink, and breathe on its own. The Spleen and Stomach then extract and refine Qi from the food and drink and the Lung gets Qi from the air. Postnatal Jing is the complex of essences thus refined and extracted. It is the material basis for the functional activity of the body’s internal organs and metabolism. The Kidneys store any surplus Jing to be released when requirestnatal Jing is continually being used by the body and replenished by food and drink. The Prenatal Jing is enriched and functions optimally only through the action of the Postnatal Jing. Without the function of the Prenatal Jing, the Postnatal Jing cannot be transformed into Qi.
Kidney Jing plays important role in physiology. It arises from both Prenatal and Postnatal Jing. It is hereditary, like Prenatal Jing and determines ones constitution. However, it is partly replenished by the Postnatal Jing. Kidney essence is stored in the Kidneys, but has fluid-like nature and circulates all over the body. Kidney Essence is said to have the following functions:
(i) It is the basis for growth, development, sexual maturation, and reproduction. — It moves in long, slow developmental cycles (men’s Essence flows in 8-year cycles; women’s in 7-years) and presides over the major phases of development in life. Kidney Jing declines naturally, producing the signs of aging, such as: hair/teeth loss, impairment of memory, etc.
(ii) It is the basis for Kidney Qi — Jing is fluid-like and therefore more Yin and so can be considered as an aspect of Kidney Yin. It forms the material basis for Kidney Yin to produce of Kidney Qi. Kidney Yin is warmed by Kidney Yang and the heat from the Ming Men to produce Kidney Qi.
(iii) Kidney Jing produces Marrow — Marrow produces bone marrow, the brain, and fills the spinal cord. (Marrow in Chinese medicine has no exact equivalent in Western Medicine). The Brain in TCM is called the “Sea of Marrow”. Therefore if Kidney Jing is weak, the brain may be undernourished, leading to poor memory or concentration, dizziness, a feeling of emptiness in the head, etc.
(iv) It determines our Constitution — Protection from exterior pathogens depends largely on the strength the Defensive (Wei Qi), as discussed below.
(v) Jing and Qi are the material foundation for Shen (Mind) — This postulate is used in Chinese medicine because Jing, Qi and Shen represent three different states of the condensation of “Qi”, from coarse, to rarified, to subtle and immaterial, respectively. If Jing and Qi are healthy and plentiful, the Mind will be happy. If both Jing and Qi are deficient, the Mind will suffer.
3. Different Types of Qi
To help students of TCM to understand “Qi,” modern TCM books started to define different “Qi” one way or another. These exploratory definitions discussed below may inspire us to think about the concept of Qi more carefully and comprehensively. They may also create new problems in understanding the true meaning of Qi and its applications in TCM, since “the Dao that can be told in words is not the eternal Dao”. However, as long as we keep it in mind that Qi is more of a multi-meaning or multi-component concept than a specific matter, energy or function, we would be less likely to deviate from the original meaning of Qi.
Some TCM books have classified the life-force energy according to its location and function in the body (2, 3). Here are some examples of the definitions of various Qi for us to start thinking this abstract concept in a more concrete way:
Prenatal Qi (Yuan Qi 元气)
Yuan Qi is said to be Jing (Essence) in the form of Qi. Yuan Qi has its root in the Kidneys and spread throughout the body by the San Jiao (Triple Burner). It is the foundation of all the Yin and Yang energies of the body. Yuan Qi, like Prenatal Jing, is hereditary, fixed in quantity, but nourished by Postnatal Jing.
Yuan Qi is the dynamic force that motivates the functional activity of internal organs, and is the foundation of vitality. It circulates through the body in the channels, relying on the transporting system of the San Jiao (Triple Burner). It is the basis of Kidney Qi, and dwells between the two Kidneys, at the Gate of Vitality (Ming Men). It facilitates transformation of Qi described below, and participates in producing Blood. It emerges and stays at the 12 Source points.
Center Qi (Zhong Qi 中气)
Energy generated from the Spleen and Stomach, whose function is to transport the Qi from food into the chest where it is combined with the Heart’s and Lungs’ Qi.
Food Qi (Gu Qi 谷气)
Food entering the Stomach is first “rotted and ripened”; then transformed into a usable form by the Spleen. The energy derived from this food essence is divided into Pure Yang Qi and Impure Yin Qi by the Spleen. The Pure Yang Qi is sent upward to the chest by the Center Qi via the Middle Burner. First, it goes to the Lungs where it combines with the Heavenly Qi to form Gathering (Zong) Qi. Then, it is transported to the Heart, where it unites with the Yuan Qi from the Kidneys to produce Blood. The turbid Yin Qi of Gu Qi is sent down by the Spleen via the Middle Burner to the Lower Burner to be further refined and excreted.
Clear Qi (Qing Qi 清气)
This is the pure energy from the Gu Qi sent by the Spleen to the Upper Burner and chest via the Middle Burner, also known as Yang Qi.
Turbid Qi (Zhuo Qi 浊气)
This is the impure energetic essence of Gu Qi transported by the Spleen via the Middle Burner to the Lower Burner to be further refined and excreted.
Gathering Qi (Zong Qi 宗气)
This is also called Chest Qi (Xiong Qi), Big Qi Da Qi) and “ Big Qi of the Chest”. The Spleen sends the pure energetic essence of Gu Qi up to the Lungs, where (with the help of Yuan Qi and Kidney Qi) it combines with air and transforms into Zong Qi.
Zong Qi nourishes the Heart and Lungs. It enhances and promotes the Lungs in controlling Qi and respiration and the Heart’s function of governing the Blood and Blood Vessels. If Zong Qi (Gathering Qi) is weak, the extremities, especially the hands, will be weak or cold. Zong Qi gathers in the throat and influences speech (which is under control of the Heart) and the strength of voice (under control of Lungs). The strength of Zong Qi can also be determined from the voice – weak (strong) voice, weak (strong) Zong Qi. It is easily affected by emotional problems, such as grief and sadness, which disperse the energy in the chest and weaken the Lungs. The Lungs and Kidney mutually assist each other via Zong Qi and Yuan Qi. Zong Qi flows downward to aid the Kidneys while Yuan Qi flows upward to aid in respiration (and the formation of Zong Qi). The chest area where Zong Qi collects is called the “Sea of Qi”. Zong Qi and the Sea of Qi are controlled by Shanzhong (Ren-17). Gathering Qi is also treated by the Heart and Lung Channels and breathing exercises.
True Qi (Zhen Qi 真气)
Zong Qi originates in the Lungs. It is transformed into Zhen Qi with the catalytic action of Yuan Qi. Zhen Qi is the last stage in the transformation and refinement of Qi. It is the Qi that circulates in the channels and also outside the body and nourishes the organs. Zhen Qi has two different forms, Ying Qi and Wei Qi.
Ying Qi (Nutritive Qi 营气)
Ying Qi nourishes the internal organs and the whole body. It spends two hours in each channel, moving through all twelve channels in a twenty four hour period (termed the Horary Cycle). During these periods, the corresponding organs are nourished and maintained by the Ying Qi.
It is closely related to Blood, and flows with Blood in the vessels as well in the channels. Ying Qi is the Qi that is activated by insertion of an acupuncture needle. It is closely related to the emotions, since it can be directed by thought.
Wei Qi (Protective Qi 卫气)
Wei Qi is fast moving, “slippery” and more Yang than Nutritive Qi. It flows primarily under the skin and in between the muscles, especially in the Tendino-Muscular meridians. Wei Qi protects the body from attack by exogenous pathogenic factors such as harsh weather conditions, microorganisms, harmful emotions, and evil spiritual forces. For example, a deficiency of Wei Qi can make someone prone to frequent colds.
There are three Wei Qi fields extending several feet from the body. All energetic forms of the body, including organs, blood vessels, nervous system, etc., can be accessed and treated through these fields.
Wei Qi warms, moistens, and aids in nourishing skin and muscles. For example, a person with a deficiency of Defensive Qi will tend to feel easily cold.
Wei Qi adjusts the opening and closing of pores; thus, regulating sweating and the body temperature. It is controlled by the Lungs, which regulates its circulation.
Deficient Wei Qi can lead to spontaneous sweating. When an exogenous pathogen (e.g., Wind-Cold) invades the exterior, the pathogen can block the pores, inhibiting the function of the Wei Qi, and blocking sweating.
Defensive Qi has its root in the Lower Burner (Kidneys). It is nourished by the Middle Burner (Stomach and Spleen) and is spread outwards by the Upper Burner (Lungs).
Wei Qi has a complex circulation pattern, of 50 cycles during a 24 hour period, 25 times in the day and 25 at night. In the daytime, Wei Qi circulates in the Exterior, but at night it goes into the Interior to protect the Yin Organs.
It is said that sleeping under an open window at night gives exogenous pathogens a better chance for attack than during the daytime, since the Exterior of the body is less well protected. Hence, it is easier to catch a cold at night than in the daytime.
Wei Qi can become thicker and extends farther out during Qigong practice. Therefore, it may take longer to move inward at night, causing some Qigong practitioners to have difficulty falling asleep after evening practice.
Upright Qi (Zheng Qi 正气)
Upright Qi is also known as Righteous Qi. This is not another type of Qi but a general term to indicate the various Qi protecting the body from invasion by Xie Qi.
Postnatal Qi (Hou Tian Zhi Qi 后天之气)
Energy derived from food and drink (from Earth) and air (from Heaven) which are cultivated after birth. Postnatal Qi depends on Prenatal Qi for development. Both form the foundation for the body’s vital energy.
Organ Qi (Zang and Fu Qi 脏腑之气)
This is the energy responsible for the functioning of the internal organs. The Yang-Fu, hollow bowels, produce Qi and Blood from food and drink. The Yin-Zang, solid viscera, store vital substances. Each organ has its own energy corresponding to one of the Five-Element energies, which respond to the universal and environmental energy fields. Thinking, feeling, metabolism and hormones can influence the Organ Qi.
1. Wiseman N. English-Chinese Chinese-English Dictionary of Chinese Medicine. Hunan, China: Hunan Publish of Science and Technology. 1996
2. Maciocia, G. Foundations of Chinese Medicine. Churchill Livingstone, New York, 1989.
3. Johnson, J. A. Chinese Medical Qigong Therapy. International Institute for Medical Qigong, Pacific Grove, 2000.
[Dr. Eisen is a retired scientist, who constructed mathematical models in medicine. He has studied and taught Judo, Shotokan Karate, Aikido, Qigong, Praying Mantis Kung Fu, and Tai Chi in different places. He took correspondence courses in Chinese herbology and studied other branches of Chinese medicine with a traditional Chinese medical doctor. He was the Director of Education of the Chinese Medicine and Acupuncture Institute in Upper Darby, PA. You can get more information about Dr. Eisen from http://home.comcast.net/~carolezak]
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