1. Introduction
Meridian theory is an important component of the basic theories of traditional Chinese medicine.
The time of birth for the meridian concept is not yet clear. There was only a brief description of the elevenmeridians in the silk manuscripts excavated from Mawangdui Han Tombs [1] , but later, around the time of the Yellow Emperor’s Canon of Medicine, the meridian theory had matured in its development. The Yellow Emperor’s Canon of Medicine established the basic framework of the twelve meridian system, depicting the twelve meridians as an inter-connected system of circulation [2] . The subsequent concepts proposed, such as the concept of “Eight Extraordinary Meridians” by the Classic on Medical Problems [3] and the concept of “Fourteen Meridians” combining the twelve meridians with Ren and Du meridians developed by Hua Shou of Yuan dynasty in the Elucidation of Fourteen Meridians [4] , was no more than supplement and extension of the meridian system in the Yellow Emperor’s Canon of Medicine.
A meridian is not an anatomical structure. Its morphology has not been in any way traced inside the human body. Even more importantly, theories of traditional Chinese medicine are constructed mainly upon the basis of philosophical thinking, emphasizing macro understanding of the body’s functional status as a whole and thus rendering the anatomical description of human structures less important or even dispensable.
The meridian theory has apparently reflected the perceptual characteristics of Chinese culture for its direct image visualization with intuitive logic, which must be a key point when we discuss the origin of meridians.
2. Several Incorrect Viewpoints about the Origin of the Meridians
It has now been widely accepted that the concept of meridians was originated from the propagated sensations produced along a channel during acupuncture or massage treatment. However, such an understanding is not true. While acupuncture stimulation can easily produce propagated sensations, the concept of meridians was conceived much earlier than the invention of acupuncture needles. The Nine-needles made their first appearance during the time of the Yellow Emperor’s Canon of Medicine when the concept of meridians had already existed. Clearly, the concept of meridians has nothing to do with the propagated sensations of acupuncture needling. In the Eleven Arms and Feet Meridians for Moxibustion, it states repeatedly that “for those with symptoms like that, so-and-so meridian should be targeted for moxibustion”. It is evident that moxibustion was the only method of treatment applied at that time, while propagated sensation, as produced by the burning of small cones of dried herbs, application of pointed stones, massage or cupping therapies, was a rare clinical phenomenon. Therefore, it is no more than a conjecture to take scattered and indefinite phenomena of propagated sensations as the origin of the circulation pathways of the “Eleven Meridians” and “Twelve Meridians”.
Similarly, the concept of meridians did not come from the generalisation and classification of human pathological phenomena, nor the induction of acupoint treatment effects. Systematic classification of human pathological phenomena can be carried out, but it would be difficult to derive the concept of meridians from such classification. As for the acupoints in early times, they form an independent system that was not connected with the meridians. The locating of acupoints was governed by the principle that “acupoint is where the pain is” which clearly reflected the unique feature of an acupoint as the site of pain, pathogen and treatment. The integration of meridians and acupoints took place during the Yellow Emperor’s Canon of Medicine era. Becoming attached to the meridians, the acupoints hence gained wider practical significance. However, as the concept of meridians was formed long before the compilation of the Yellow Emperor’s Canon of Medicine, it would only create more confusion about the origin of meridians if the meridians and acupoints were mixed together.
3. The Meridian Concept Stems from the Philosophy Idea
In fact, the concept of meridians was derived merely from a very simple philosophical thinking: human and nature bear resemblance to each other, the human body must therefore have a system of Qi and blood circulation similar to the flow of rivers and lakes in nature.
Ancient China was an agricultural society, the condition of an irrigation system determines the harvest. The legend of Dayu has highlighted the importance of irrigation works to a nation’s prospect and people’s livelihood. The flow of water over streams and mountains is in itself a natural phenomenon and is a part of the natural environment; it is also closely related to agricultural production. As the way of human beings resembles that of heaven, the human body will certainly have a system of Qi and blood circulation similar to that of rivers and lakes in nature. The Yellow Emperor’s Canon of Medicine has made it clear that as the Earth has four seas in the east, south, west and north, the human body must also have four “seas”, namely, the sea of Shuigu (food digestion), the sea of Twelve Meridians, the sea of Qi and the sea of Marrow, and as there are twelve rivers on earth, so there must be twelve meridians inside the human body.
Drawing analogy between the human body and nature is an evident feature of the philosophy of traditional Chinese medicine.
4. Qigong Practice Laid the Foundation of Meridian Theory
A meridian is a channel of Qi and blood circulation and that is the most basic nature of a meridian. Meridian is the collective name for meridians and collaterals in general, referring to the many blood vessels criss-crossing the human body. The vertical ones are called “meridians” while the horizontal ones are called “collaterals”. Originally, “Mai” means blood vessels, but in meridian theory it also means the main channels for Qi circulation.
Undoubtedly, the origin of meridians is closely related to the imageries derived by ancient physicians experiencing the circulation of Qi in their bodies during Qigong practice. As the renowned practitioner of Ming dynasty Li Shizhen said in the Compendium of Materia Medica, “the interior channels of the body can only be detected by a self-observing person.” [5] In the silk manuscripts excavated from Mawangdui Han Tombs, there was an illustrated guide to physical and breathing exercise with drawings of 44 individuals from different sexes and ages practicing a variety of movements. The bamboo manuscripts excavated from Zhangjiashan Han Tombs in Hubei have documented the theory, key movement guides and practical application of physical and breathing exercise [6] . The 45-word inscription engraved on the ancient jade pendant for promoting Qi circulation, now being kept at the Tianjin History Museum, embodies a complete description of the Qi circulation from the beginning to the end of a Qigong practice [7] . All these historical materials have shown that Qigong had already become very popular long before the Yellow Emperor’s Canon of Medicine era.
From the experience of Qigong practitioners, it is evident that different Qigong practitioners derive different imageries about the meridians. Comparing the circulation pathways of the twelve meridians as documented by the Meridians of the Spiritual Pivot, the meridian channels for Qi circulation as perceived during Qigong practice were basically similar to that of the propagated sensations along the meridians. Specifically, the route of Qi circulation along the four limbs in Qigong practice was largely the same as that of the meridian pathways, while that of the chest and abdomen showed certain inconsistencies and that of the head and face showed considerable inconsistencies.
The different imageries perceived by Qigong practitioners have not only explained the existence of two different versions of the meridian pathways as documented by the silk manuscripts of the Eleven Arms and Feet Meridians for Moxibustion and the Eleven Yin and Yang Meridians for Moxibustion excavated from Mawangdui Han Tombs, but also showed the distribution of the twelve meridians pathways in different parts of the body as described by the Meridians of the Spiritual Pivot.
Take the pathways of the Gallbladder Meridian as an example, the description by the Meridians of the Spiritual Pivot is quite clear: there is only one pathway on each lower limb, but is divided into two pathways when it comes to the chest and abdomen, and three on the head and face. In the Elucidation of the Fourteen Meridians written by Hua Sou in Yuan Dynasty, the pathway of this meridian on the head has even turned into three divergent folds of lines. For example, the meridian pathway after Wangu (GB12) does not move on to reach the neighbouring Fengchi (GB20), but instead goes up front to Yangbai (GB14) on the forehead before turning down to Fengchi at the back.
The description by the Elucidation of the Fourteen Meridians can only be regarded as an illustration of the meridian pathways with meridians and acupoints combined, but it should not be taken as the ultimate version. In spite of this, the multiple meridian pathways on the head have reflected largely the actual Qi circulation in meridian channels as perceived by practitioners during Qigong exercise. The meridian pathways in the four limbs are largely clear while that in the chest and the abdomen are not quite clear, and that on the face and head are mostly not clear. Different Qigong practitioners experience different imageries of Qi circulation and therefore have different documentation of the meridian pathways. The pathways of the twelve meridians described by the Meridians of the Spiritual Pivot must be the consolidated result of the observations made from a variety of Qigong practice.
5. Conclusions
The concept of meridian should be originated from the observations of human life phenomena by ancient physicians. However, such observations were only vague perceptual understanding. The meridian theory therefore has the typical characteristics of ancient Chinese philosophy. It is constructed upon the perceptual experience gained from Qigong practice as well as the analogical extensions of the flow of rivers in nature and irrigation systems in agriculture. It gives rise to a model of Qi and blood circulation that is abstract and yet concrete, dialectic and yet intuitive, definite and yet vague, integrated and yet independent, hence laying the foundation for the development of acupuncture theories.
In terms of concrete structures, meridians are no more than “blood vessels”. However, in macro perspective, the function of Qi and blood circulation represents the basic features of human vitality, and elucidates the intrinsic connections among Yin and Yang, the five elements, viscera, Qi and blood and other traditional Chinese medicine theories, thereby having a profound influence on the overall theoretical construction of traditional Chinese medicine.