Section two theory oF Five elementS

Theory of five elements is a common philosophy theory in ancient China. It originated from the observation and thoughts of the nature by the ancients.According to the theory, internal systems of many things in the nature can be divided into five elements-wood, fire, earth, metal and water.These five elements promote and restrict each other so that the internal system can maintain stable.Besides, things attributing to one element but with different forms have specific relativity and correspondence.In general, the theory of five elements is a theory that studies relationships within the things and between the things.

I Basic contents of the theory of fve elements

1.Connotation and formation of fve elements

Wu Xing（five elements）refers to the movement and changes of wood, fire, earth, metal and water."Wu"here refers to five basic substances, phenomena or attributions of wood, fire, earth, metal and water;"xing"means movement and changes in Chinese. The formation of the theory of five elements may have some connection with the ancient concept of"wu cai"（five materials）.The ancients realized that wood, fire, earth, metal and water were indispensable basic substances or phenomena in daily life and raised the concept of"five materials".For example, Legend of Spring and Autumn Century by Zuo Qiuming（Zuo Zhuan）states"The five kinds of materials in nature are all used by people.Each of them is indispensable".The simple realization had been sublimated to the level of philosophy and become a philosophical term.Thus five elements have become five basic attributes that are used to generalize things in the universe and to interpret the relationships between the things.

2.Characteristics of fve elements

Wood, fire, earth, metal and water originally referred to five things or phenomena. But after the generalization of their characteristics by philosophers, they are no longer used to refer to specific things, but are instrumental terms representing different properties of things.

The Book of History·The Great Plan（Shang Shu·Hong Fan）says"Water has the nature of moistening and flowing downwards;fire has the nature of flaring up;wood has the nature of bending and straightening;metal has the nature of changing and transforming;Earth has the nature of sowing and reaping."These generalizations are accepted and extended in meaning by the descendants.

Characteristics of wood:"Wood has the nature of bending and straightening"means that wood has the characteristics of growing freely and unfolding. Its connotation is that wood is growing, spreading and orderly smooth.All things with such characteristics attribute to wood.

Characteristics of fire:"Fire has the nature of flaring up"."Flare"means to burn hot;"up"means upwards. Its connotation is that fire is warm and hot, upwards and ascending.All things with such characteristics attribute to fire.

Characteristics of earth:"Earth has the nature of sowing and reaping". It means that the earth can be used for sowing and harvesting by mankind, which is the basis of the development of human beings.Its connotation is that earth is generating, bearing and receiving.All things with such characteristics attribute to earth.

Characteristics of metal:"Metal has the nature of changing and transforming". It is hard to interpret"Changing and transforming".But it can be understood as obeying and transforming.Metals mainly come from smelting and processing of the minerals.It is heavy and often used for felling and killing.Its connotation is that metal is chilling, astringing and clearing.All things with such characteristics attribute to metal.

Characteristics of water:"Water has the nature of moistening and flowing downwards"."Moistening"means to moisten things and keep them moist with water;"downwards"means that water is always going down. Its connotation is that water is cold, cool, moistening and going downwards.All things with such characteristics attribute to water.

3.Classifcation of things according to the theory of fve elements

The ancient philosophers divided things in various systems of the nature into five groups based on the theory of five elements and studied the relationships between these five elements. Thus five-element system is established.

The thinking methods of classification of things according to five elements are mainly the following two types:

The first is direct analogy method. It is to attribute something to one element, whose symptom is similar to the characteristics of the element.For example, in terms of five directions, the east is the place where the sun rises, full of vitality, which is similar to the growing characteristic of wood, therefore, the east attributes to wood;the climate in the south is hot, which is similar to the flaring characteristics of fire, therefore, the south attributes to fire;the plateau in the west is the place where the sun sets, vitality littering, which is similar to the killing characteristic of metal, therefore, the west attribute to metal;the climate in the north is cold and animals there hibernate long, which is similar to the cold, cool and static reserving characteristic of water, therefore, the north attributes to water;in the central plain, the climate is moderate and is benefit for the growth of living things, which is similar to the generating and bearing characteristic of earth, therefore, the central attributes to earth.

The second is indirect deductive method. For some things which are hard to differentiate their properties of five elements with direct analogy method, things whose properties of five elements are already known and which have close relations with them can be used to deduct the properties of the latter to the former.For example, the liver is known attributing to wood.Since the liver is connected with gallbladder, tendons, nails and eyes, it can be deducted that the gallbladder, the tendons, the nails and the eyes all attribute to wood;for the same reason, the heart attributes to fire and the small intestine, the pulse, the face and the tongue connected with the heart also attribute to fire;the spleen attributes to earth, and the stomach, the muscles, the lip and the mouth connected with the spleen also attribute to earth;the lung attributes to metal, and the large intestine, the skin, the hair and the nose connected with the lung also attribute to metal;the kidney attributes to water, and the bladder, the bone, the hair, the ears and two lower orifices connected with the kidney also attribute to water.

Based on classification of five elements, various complex systems in thenature and the body can be divided into five subsystems, i. e.wood, fire, earth, metal and water（Details see the following Table 1-1）.However, such classification is only based on concept of wholism so as to study and solve the whole problems better.

Table 1-1 Table of the Systems of Five Elements

Table 1-1 Table of the System of Five Elements（continued）

Table 1-1 Table of the System of Five Elements（continued）

The theory of five elements not only reveals that the interior of each objective system can be divided into five, but also emphasizes the correspondingcorrelations between each system. That is to say, after making longitudinal classification of the objective things, the ancients also made lateral connection among things unrelated to each other superficially and creatively constructed the

Table 1-1 Table of the System of Five Elements（continued）

systems of five elements, as manifested in Table 1-1. From the table not only the internal elements of each system could be seen in line with the vertical column, but also the possible connections between the elements belonging to different fields can be explored and grasped in line with the lateral column, for they are in the systems of the same line.Thus life activities are connected with things and phenomena in the nature, and the mode of thinking with five elements, which is efficient in relating the interior and exterior environments of the body, is formed to explore the unity of the body and the natural environment.

4.Relations between fve elements

The theory of five elements mainly studies the relations between five elements, including mutual generation and restriction, promotion and restriction, alternate preponderance, over-restriction and reverse restriction, as well as affecting between mother and child of five elements.

4.1　Mutual generation and restriction of fve elements

The normal state of a system depends on the dynamic balance within the things, i. e.it is the normal adjusting relations of orderly generation and restriction between five elements that maintain the development of the whole system.

4.1.1　Mutual generation of fve elements

Mutual generation refers to the passing generating and promoting relationship between wood, fire, earth, metal and water in order.

The order of mutual generation of five elements is:wood generates fire, fire generates earth, earth generates metal, metal generates water and water generates wood. Classic of Difficult Issues（Nan Jing）compares such relationship to"mother-child"relationship vividly, i.e."the one generating"is"mother"and"the one to be generated"is"child".For example, wood can generate fire, therefore, wood is the"mother"of fire and fire is the"child"of wood.

4.1.2　Mutual restriction of fve elements

Mutual restriction refers to the passing restricting and restraining relationship between wood, fire, earth, metal and water in order.

The order of mutual restriction of five elements is:wood restricts earth, earth restricts water, water restricts fire, fire restricts metal and metal restricts wood. Canon of Medicine（Nei Jing）names such relationship as"being restricted"and"being unrestricted".All that"to restrict me"is"my""unrestricted";all that"to be restricted"is"my""restricted",i.e.the one"to restrict me"is the"unrestricted"and the one"to be restricted"is the"restricted".Take water as the example.Earth is the"unrestricted"of water and fire is the"restricted"of water.

4.2　Promotion and restriction, and alternate preponderance of fve elements

4.2.1　Promotion and restriction of fve elements

Promotion and restriction refers that five elements promote and restrict each other, which maintains the steady and ordered development of things in nature.

Plain Questions·On the Changes of Six Qi（Su Wen·Liu Wei Zhi Da Lun）points out"Excess damages, to restrict can make it moderate and in harmony, so that the normal generation of things can be maintained". It emphasizes that both excess and deficiency should be heeded in generation and development of thethings and that it is necessary to restrict things going beyond the normal limit, i.e.both mutual generation and restriction of five elements are indispensable.Without generation, there would be no the occurrence and growth of the things;without restriction, things could not maintain normal coordinating relationship among them.Therefore, generation and restriction must be both opposite and complementary to each other i.e.there is restriction in generation and generation in restriction.Only in this way, things can maintain their balance and coordination and change and develop in order steadily.Zhang Jiebin, a physician in Ming Dynasty, pointed out in The Illustrated Wings of the Classified Canon（Volume 1）（Lei Jing Tu Yi·Yun Qi Shang）"The mechanism of the nature cannot exist without generation or restriction.No generation, there would be no source of breeding;no restriction, excess would grow and damage".

The principle of promotion and restriction of five elements is:When one of five elements is in excess, restriction to it is to follow soon to prevent excess resulting in injury, i. e.to restrict in mutual generation and to develop in mutual restriction.To be precise, wood generates fire, fire generates earth, but wood can restrict earth;fire generates earth, earth generates metal, but fire can restrict metal;earth generates metal, metal generates water, but earth can restrict water;metal generates water and water generates wood, but metal can restrict wood;water generates wood, wood generates fire, but water can restrict fire.So moves in circle.

4.2.2　Alternate preponderance of fve elements

Alternate preponderance of five elements means that the excess of one of five elements will inevitably results in retaliatory restriction of its"unrestricted",which will in turn restore gradually the coordinating and steady development state of five elements.

Alternate preponderance of five elements refers to the self-regulation among five elements according to mutual restricting principle."Restricting qi"means that one of five elements is too excessive, i. e.absolutely excessive or relatively excessive."Counter-restricting qi"is caused by the appearance of"restricting qi",i.e.the unrestricted of the restricting qi."Restricting qi"comes up first, and then gradually"counter-restricting qi"appears gradually to take vengeance on the"restricting qi"and make it no more excessive.For example, if wood is in excess, it is the restricting qi, whose counter-restricting qi is metal;if fire is in excess, it is the restricting qi, whose counter-restricting qi is water;if earth is in excess, it is the restricting qi, whose counter-restricting qi is wood;if metal is in excess, it is the restricting qi, whose counter-restricting qi is fire;if water is in excess, it is the restricting qi, whose counter-restricting qi is earth.

The specific case of alternate preponderance of five elements is like this:When one of five elements is excessive, they will restrict one another in order of restriction and cause their unrestricted（counter-restricting qi）gradually excessive to restrict the excess of the element and make it normal. Take excess of wood as the example:excess of wood causes deficiency of earth;which in turn causes excess of water;excess of water causes deficiency of fire, which in turn causes excess of metal;excessive metal will restrict wood and calm down excess of wood.Now the excessive wood is restricting qi, while excessive metal is counter-restricting qi.Excess of metal is the retaliation against excess of wood.Preponderances of the other four elements may be deduced by analogy.

With the adjusting mechanism of restricting and counter-restricting, when imbalance of the part appears, the system of five elements can readjust automatically to maintain the balance of the whole.

4.3　Over-restriction and reverse restriction of fve elements

4.3.1　Over-restriction

Over-restriction means that five elements restrict one another too much, i. e.to surpass the normal limit.Its order and direction is the same as that of restriction.Any one of the following three conditions may cause over-restriction of five elements:first, the power of the"unrestricted"is too strong;second, the power of the"restricted"is too weak;third, the"unrestricted"is over-excessive and the"restricted"is deficient.Take wood restricting earth as the example.Wood is the unrestricted of earth, and earth is the restricted of wood.If wood is over-excessive or earth is deficient, or both wood is over-excessive and earth is deficient, over-restriction of"wood over-restricting earth"may appear.

4.3.2　Reverse restriction

Reverse restriction refers to the adverse restriction. Its order and direction is reverse to that of restriction.Any one of the following three conditions may cause reverse restriction of five elements:first, the power of the"unrestricted"is deficient;second, the power of the"restricted"is too strong, i.e.to surpass the normal limit;third, the"restricted"is over-excessive and the"unrestricted"is deficient.Take metal restricting wood as the example.Metal is the"unrestricted"of wood, and wood is the"restricted"of metal.No matter the deficiency of the"unrestricted"metal, or the excess of the"restricted"wood, or both the deficiency of metal and the excess of wood, all can cause the reverse restriction of"wood reverse restricting metal".

"Excess"or"deficiency"of any one of five elements can affect the other four. Let's take over-excess of metal as an example（see Figure 1-1）.

4.4　Affecting between mother and child of fve elements.

4.4.1　The diseased mother-organ affecting the child-organ

The diseased mother-organ affecting the child-organ means that the abnormality of one of five elements may involve its child element and make it abnormal too. It is mainly caused by deficiency of the mother element.For example, water generates wood, then water is the mother and wood is the child.If water is insufficient and cannot generate wood, deficiency of wood may be caused.And finally the water may be exhausted and the wood may wither away, i.e.both mother and child are in deficiency.

4.4.2　The diseased child-organ involving the mother-organ

The diseased child-organ involving the mother-organ means that the abnormality of one of five elements may involve its mother element and causes both the mother and child elements abnormal. There are two cases:one is that the excess of child element causes the excess of mother element, the result of which is that both mother and child elements are in excess.This is called"child organ's disorder involving its mother organ".For example, excess of fire results in excess of wood, and finally both wood and fire are in excess.The other one is that the child element is weak and involves its mother element, causing the mother element also in deficiency, the result of which is that both mother and child elements are in deficiency.This is called"child organ robbing healthy qi of mother organ".For example, deficiency of wood results in deficiency of water, and finally both wood and water are in deficiency.

II Application of the theory of five elements in TCM

The theory of five elements tries to interpret the generating and restricting relationship among things with"five"as the base number. In nature, it is a kind of theoretical model, guiding people to know the complex and wide connections among things in the universe in a simple way and to explore the rules.As a simple concept of nature and methodology, it is mainly manifested in the field of TCM as:analyzing physiological functions and pathological phenomena of human body, inspiring diagnosis and treatment ideas, connecting parts of the body with the factors of the exterior environment, exploring the influences of the rules of fivemovements and six climates in nature on the system of five zang-organs and so on.It has advanced the perception of TCM that human body as well as human beings and the exterior environment are completely a whole, which makes the wholism concept adopted by TCM more specific and substantial.

1.Explaining the physiology of human body

1.1　Analyzing the physiological functions of fve zang-organs

With the limitation of historical conditions, it was impossible for the ancient Chinese physicians to know the specific functions of the internal organs of the body with microscopic quantitative research methods;therefore, they borrowed the theory of five elements to analyze the important physiological functions of five zang-organs. For example, the nature of wood is spreading and smooth and the liver attributes to wood, so the liver prefers smoothness to depression and governs conveyance and dispersion of qi activity;fire is warm and hot, and heart attributes to fire, so heart yang can warm the body;earth generates all things, so the spleen attributing to earth has the functions of digesting and producing nourishment;metal is chilling and clearing, so the lung attributing to metal can clear turbid phlegm;water is moistening and flowing downwards and the kidney attributes to water, so the kidney stores essence and has the characteristic of closing and hiding.

1.2　Explaining the relationship among fve zang-organs

Traditional Chinese medicine explains the relationships of mutual promotion and restriction among five zang-organs with the theory of intergeneration and restriction of five elements, which has furthered the understanding about the whole communication of the body.

1.2.1　Explaining the coordinating relationship among five zang-organs with intergeneration of fve elements

For example, the relationship of water generating wood can be used tointerpret kidney essence generating yin and blood and nourishing the liver;the relationship of wood generating fire can be used to interpret the function of liver storing blood and adjusting the blood flow to assist the heart promoting circulation of blood;the relationship of metal generating water can be used to explain the function of liver governing water flow and assisting the kidney to complete water metabolism.

1.2.2　Explaining the restricting relationship among five zang-organs with mutual restriction of fve elements

Five zang-organs not only nourish and generate each other in coordination, but also restrict each other. For example, the liver is spreading and smooth and can dredge the spleen;the kidney restricts the heart to prevent heart excess, which can represent the relationship of water restricting fire.

1.3　Classifying the organs and tissues of human body

Based on the relationship of five zang-organs corresponding to five elements, with indirect deductive method, traditional Chinese medicine attributes the organs and tissues of the body to five elements according to their functions and characteristics. With five zang-organs（the liver, the heart, the spleen, the lung and the kidney）as the center, matched up by five fu-organs（the gallbladder, the small intestine, the stomach, the large intestine and the bladder）,five body constituents（tendon, vessel, muscle, skin and bone）,the five sense organs（eyes, tongue, mouth, nose and ears）as well as five luster（hands and feet, face, lips, fine hair, hair）,the system of zang-fu and body constituent is formed, which established the theoretical system of theory of zang-fu manifestation.

1.4　Explaining the unity of human and nature

The theory of five elements employs correspondence between human and nature and like attracting like to range human body and various things and phenomena in the nature into the five subsystem, and then associates five zang-organs, six fu-organs, five body constituents and five sense organs respectivelywith five directions, five seasons, five tastes, five colors in the nature. For example, the excessive liver qi in spring unifies the liver of human body with spring qi in the nature, which represents the concept of wholism of unity between the internal and external environment of the body.

2.Explaining the rules of disease changes among five zang-organs

"Changes"refer to the dynamic spread and changes of diseases in different organs of the body. Five zang-organs not only closely relate to each other physiologically but also affect each other pathologically, the rules of which can be explored from the perspective of abnormal relationship of five elements, i.e.under abnormal circumstance, disease progress of affecting between mother and child, as well as over-restriction and reverse restriction may arise among five zang-organs.

2.1　Pathological changes due to affecting between mother and child

Such type of pathological changes refer to the disease changes caused by the destruction of intergeneration among five zang-organs, including"the diseased mother-organ affecting the child-organ"and"the diseased child-organ involving the mother-organ".

2.1.1　The diseased mother-organ affecting the child-organ

The diseased mother-organ affecting the child-organ refers to the process of diseases transferring from mother organ to child organ. For example, if the spleen deficiency（earth）lasts long, the patient will have lung（metal）diseases of cough, cough up phlegm and asthma on the basis of long-term inappetence and diarrhea.This is the disease changing process of diseased mother-organ（the spleen earth）to affecting child-organ（the lung metal）.

2.1.2　The diseased child-organ involving the mother-organ

The diseased child-organ involving the mother-organ refers to the process of diseases transferring from child-organ to mother-organ. For example, if the live disease hypochondriac pain lasts long, it will affect the kidney and cause the kidney deficiency symptom of aching pain in the waist and knees.This is the disease changing process of the disease of child-organ（the liver wood）involving mother organ（the kidney water）.

2.2　Pathological changes due to over-restriction and reverse restriction

Pathological changes due to over-restriction and reverse restriction refer to the disease changes caused by abnormal restriction among five zang-organs, including over-restriction and reverse restriction.

2.2.1　Over-restriction

Over-restriction is the changing process of the disease of one zang-organ affecting the zang-organ which is its restricted. There are three reasons for this:first, one zang-organ is so excessive that it over-restricts the zang-organ it restricts;second, one zang-organ is so weak that it cannot bear the normal restriction of its unrestricted organ, which causes over-restriction;third, one zang-organ is too excessive and its restricted organ is deficient, which causes much more restriction.Generally the first two cases are more common.Take the restricting relationship between the liver wood and the spleen earth as the example.There are two cases of changes due to over-restriction:"excessive wood over-restricts earth"（i.e.the liver over-restricts the spleen）and"deficient earth is over-restricted by wood"（i.e.the deficient spleen is over-restricted by the liver）.When the stagnation or adverse flow of liver qi affects the transportation and transformation of the spleen and the stomach, syndromes of distressing fullness in chest and hypochondrium, epigastric and abdominal pain, acid regurgitation and diarrhea would appear.It is"excessive wood over-restricts earth".Otherwise, if the spleen and the stomach are deficient first and cannot tolerate the restriction of liver qi, syndromes of dizziness, tiredness, anorexia, belching, abdominal distension, abdominal pain and diarrhea may appear.It is"deficient earth is over-restricted by wood".

2.2.2　Reverse restriction

Reverse restriction is the changing process of the disease of one zang-organ affecting the zang-organ which is its unrestricted. It is also called"disease caused by reverse restriction".There are also three cases of reverse restriction among five zang-organs, i.e.reverse restriction caused by excess, reverse restriction caused by deficiency and reverse restriction caused by both excess and deficiency.Generally the first two cases are more common.Reverse restriction caused by excess means that when one zang-organ is over excessive, its unrestricted zang-organ would be incompetent to restrict it and be restricted by it instead.For example, the lung metal can restrict the liver wood, but if violent rage causes hyperactivity of liver fire, lung metal would be unable to restrict liver wood and be reversely restricted by liver fire.Syndromes of cough with dyspnea, hemoptysis would come up in accompany with hot-temper and red face and eyes.This is"wood fire impairs metal".Reverse restriction caused by deficiency means that when one zang-organ is in deficiency, its restricted zang-organ would restrict it instead.For example, if the deficient spleen earth cannot restrict the kidney water, syndrome of general edema would appear after anorexia and diarrhea.This is called"deficient wood is impaired by water".In brief, diseases of five zang-organs can be transformed and changed.Disease of one zang-organ can affect the other four zang-organs through different mechanism（see figure 1-2）;any zang-organ can also be affected by the pathological changes of the other four zang-organs.

Since the human body is very complex, in clinical practice, we should not rigidly adhere to the theory of five elements, but think about the actual situation of the patient such as the specific features of the disease and the patient's constitution so as to conduct a comprehensive analysis and grasp the different situations of different disease transformation.

3.Guiding the diagnosis of diseases

Human body is an organic whole. When the pathogenic factors invade the internal organs, it can be reflected by the corresponding exterior tissues or organs through meridians and collaterals, qi and blood, which is manifested as the abnormal changes of the complexion, voice, pulse, constituent and posture.Therefore, the theory of five elements can be employed to analyze the information collected with four diagnostic methods so that they can be used as the basis of diagnosing visceral lesions.

3.1　Guiding the location diagnosis of diseases

In clinic, the location of the disease in five zang-organs is determined according to the clinical syndromes manifested by five colors, five pulses and five tastes under the guidance of the theory of five elements. For example, the symptoms of blue face, sour-liking or sour taste in mouth and wiry pulse can be diagnosed as the disease in the liver;the symptoms of bitter taste in mouth, red face and rapid and surging pulse can be diagnosed as the excess of heart fire.

3.2　Judging the changing tendency of diseases

In clinic, the changing tendency of diseases is often judged from the five-element attribution of the pulse and the complexion according to the theory ofrestriction of five elements. For example, if the patient with deficient spleen has the symptoms of blue face and wiry pulse in the progress of the disease, it can be judged that the liver wood over-restricts the spleen earth（deficient earth is over-restricted by wood）.

3.3　Speculating the disease prognosis and conversion

In clinical practice, the theory of over-restriction and counter-restriction of the five elements can be used to speculate disease prognosis from the generating and restricting relationship among the complexion and pulses of the patient. For example, a patient attacked by liver disease has blue face and string-like pulse, and it is the complexion corresponding with the pulse.If the pulse is taken as floating pulse, it is"inter-restricting pulse"（metal restricts wood）.This is a deteriorating case, which shows that the disease is serious.If the pulse is taken as sunken pulse, it is"inter-promoting pulse"（water generates wood）.This is a favorable case, which means the disease is mild.However, with the development of medicine, the disease which is diagnosed as a serious one in the past is not necessarily the disease that can not be cured in today's society, so when applying the theory of five elements to peculate the disease prognosis and conversion, the experience of the ancient physicians can not be copied mechanically.

4.Guiding the treatment of diseases

The theory of five elements can serve as the guide to treatment of diseases, which is mainly manifested in controlling disease progress, determining treating principle, and guiding viscera medication.

4.1　Controlling disease progress in fve zang-organs

Human body is an organic whole, so in disease development process, disease of one zang-organ often affects the other four zang-organs. Therefore, besides treating the diseased zang-organ, corresponding preventing measures should also be taken based on the over-restriction and counter-restriction principles, to prevent the aggravation of the disease, i.e.to eliminate its effect in the local.For example, if the liver is sick, theoretically it may affect the heart and the kidney according to the correlating rules;it may also affect the spleen and the lung according to the over-restriction and counter-restriction principle.If it is syndrome of excessive liver qi, in clinical it is commonly seen as the disease progress of excessive wood over-restricting earth, or excessive wood counter-restricting metal.Therefore, while dredging and stabilizing the excessive liver wood, physicians should also try to supplement spleen earth, or to assist lung metal so as to make good prevention before the lung qi over-restricts the spleen or counter-restricts the lung.

4.2　Determining the therapeutic principles for five zang-organ diseases

The rapeutic principles are the general guiding ideas for treating diseases. When determining the therapeutic principles based on the relevant part of the theory of five elements, there are two aspects listed in the following:

4.2.1　Determining the therapeutic principles based on the theory of intergeneration

Application of the theory of intergeneration of five elements in determining therapeutic principles is mainly represented by the principle of"If one zang-organ is in deficiency, its mother organ should be supplemented;while if it is in excess, its childe organ should be purged"made in Classic of Difficult Issues·69thIssue（Nan Jing·Liu Shi Jiu Nan）. The so called"supplementing mother organ"aims at treating the deficiency syndrome caused by imbalance between mother and child organs.For example, deficient lung qi can be indirectly assisted by supplementing spleen qi.The so called"purging child organ"aims at treating the excessive syndrome caused by the abnormal relationship between mother and child organs.For example, the liver heat syndrome can be indirectly eliminated by clearing heart fire.

4.2.2　Determining the therapeutic principles based on the theory of inter-restriction

Application of the theory of inter-restriction of five elements in determining therapeutic principles is mainly represented by the therapeutic principle of"suppressing the strong and helping the weak". No matter"over-restriction"or"counter-restriction",there exists the situation that one side is too strong and（or）the other is too weak.Only by suppressing the strong side and helping the weak side can the normal inter-restricting relationship between them be restored.This is the therapeutic principle of"suppressing the strong and helping the weak".For example, when treating excessive liver qi（wood）over-restricting spleen earth, therapeutic method of soothing the liver can be used to suppress the excessive qi of liver wood;meanwhile, method of invigorating and nourishing the spleen can be used to help the deficient qi of spleen earth.Only in this way can the normal inter-restriction relationship between the liver and the spleen be completely restored.

4.3　Developing specifc treating methods for diseases of fve zang-organs

After determining the therapeutic principles, specific treatment methods can also be developed for specific syndromes based on the theory of five elements:

4.3.1　Treating method based on the principle of"If one zang-organ is in defciency, its mother organ should be supplemented"

For example, the method of"enriching water to moisten wood"is the treating method to supplement the liver through nourishing the kidney, which can be used for yin deficiency syndrome of the liver and the kidney or syndrome of liver yang hyperactivity;the method of"enriching earth to restrict water"is the treating method to supplement the lung metal through invigorating the spleen earth, which can be used for qi deficiency syndrome of the lung and the spleen;the method of"mutual generation of metal and water"is the treating method to nourish the kidney through nourishing the lung, which can be used for yin deficiency syndrome of the lung and the kidney.

4.3.2　Treating method based on the principle of"suppressing the strong and helping the weak"

For example, the method of"restricting wood to help earth"can be used for syndrome of liver exuberance and spleen deficiency or syndrome of invasion of stomach by liver qi, i. e.to soothe liver and invigorate spleen, or to soothe liver and harmonize stomach;the method of"assisting metal and calming wood"can be used for syndrome of liver fire invading lung, i.e.to clear liver fire so as to eliminate lung heat;the method of"purging the south and nourishing the north"can be used for syndrome of deficiency of kidney yin caused by exuberance of heart fire（The heart attributes to fire and corresponds to the south of five directions;the kidney attributes to water and corresponds to the north of five directions）,i.e.to clear and purge heart fire as well as to nourish kidney yin.

4.4　Guiding selection of acupoints

Science of acupuncture and moxibustion determines the attribution of five elements for their respective"five transport points"of the twelve regular meridians, i. e.the five specific acupoints of four extremities-well point, spring point, stream point, river point and sea point.To treat zang-fu-organ syndromes, the acupuncture points will be chosen with reference to the intergeneration and inter-restriction rules among five elements.For example, in terms of syndrome of liver deficiency, according to the principle of"If one zang-organ is in deficiency, its mother organ should be supplemented",the sea point（water point）Yingu of kidney meridian or the sea point（water point）Ququan of the same meridian should be chosen to treat with reinforcing needling therapy.In terms of syndrome of liver excess, according to the principle of"If one zang-organ is in excess, its child organ should be purged",the spring point（fire point）Shaofu of heart meridian or the spring point（fire point）Xingjian of the same meridian should be chosen to treat with purging needling therapy.

4.5　Guiding treatment of emotional diseases

The five common emotional activities of human beings are controlled by the five zang-organs and attribute respectively to the five elements. Abnormal emotional activities will often injure the corresponding internal organs.Accordingto the inter-restriction principle of the theory of five elements, different emotional variations can restrict each other, i.e.the therapy of"restricting emotion with emotion"can be employed to treat mental diseases caused by emotional disorders.The specific principles can be found in Plain Questions·On Yin and Yang Corresponding with Natural Phenomena（Su Wen·Yin Yang Ying Xiang Da Lun）:"Anger impairs the liver, grief exceeds anger;excessive joy impairs the heart, terror exceeds joy;anxiety impairs the spleen, anger exceeds anxiety;melancholy impairs the lung, joy exceeds melancholy;terror impairs the kidney, anxiety exceeds terror".

4.6　Guiding medicine administration for zang-fu organs

Our ancients attributed the five colors and the five tastes of medicines to the five elements. Based on the concept of"like attracts like",they believed that medicines attributing to an element from the aspect of color or taste may have some close relations with zang-fu organs attributing to the same element;therefore, they could affect easily the corresponding zang-fu meridians and tissues to adjust their functions.For example, medicines with green color and sour taste attribute to wood and can go easily into and function on liver and its meridians, such as sour Baishao functioning to nourish liver blood;medicines with red color and bitter taste attribute to fire and can go easily into and function on heart and its meridians, such as red Zhusha entering the heart and tranquilizing the nerves;medicines with yellow color and sweet taste attribute to fire and can go easily into and function on spleen and its meridians, such as sweet Huangqi entering the spleen and supplementing qi;medicines with white color and pungent taste attribute to metal and can go easily into and function on lung and its meridians, such as Shigao entering the lung and purging heat;medicines with black color and salty taste can go easily into and function on kidney and its meridians, such as black and salty Biejia going into the kidney and nourishing kidney yin.

Summary

Yin-yang theory and the theory of five elements all belong to ancientphilosophical category, but each of them employs different philosophical theories and thinking patterns to understand the rules of lives. Yin-yang theory employs the law of the unity of opposites to illustrate the relationships of inter-restriction, inter-dependence, inter-promotion, inter-containing and interaction, waxing and waning as well as spontaneous harmonization and balance of two aspects of things.In terms of rules of human lives, yin-yang theory thinks that the human body is an organic whole as the unity of opposites, and that life activities are the representation of the movement of unity of opposites of both yin and yang;therefore, yin-yang theory is the basic method for TCM to understand the physiological functions and the pathological changes of human body, as well as the basic method to guide clinical diagnosis and disease prevention, which covers various aspects of the basic theories and clinical research of traditional Chinese medicine.

The theory of five elements analyzes the occurrence and development rules of things with"five"as the base number and according to the intergeneration and inter-restriction principles of wood, fire, earth, metal and water. It thinks that the universe is a whole composed by wood, fire, earth, metal and water through intergeneration and inter-restriction.In the field of traditional Chinese medicine, five zang-organs are attributed to five elements according to their functional characteristics.And then they are related with six fu-organs, five body constituents, five sense organs and five emotions to form five functional systems, the dynamic balance among which is maintained through intergeneration and inter-restriction of five elements.

Though different from each other, yin-yang theory and the theory of five elements are utilized comprehensively. When discussing yin-yang theory, the theory of five elements is also mentioned and vice versa.So only when they are combined together can life activities be explained thoroughly.When analyzing the physiological functions of zang-fu organs, zang-organs are considered to be yin and fu-organs are yang.Each zang-organ can also be divided into yin and yang, such as kidney yin and kidney yang, heart yin and heart yang, and so on.When analyzing pathogenesis, excess or deficiency of yin and yang should also be connected with intergeneration, inter-restriction, over-restriction and counter-restriction of five elements.For example, deficiency of kidney yin can not nourish liver wood, which will result in hyperactivity of liver yang, even transformation of excessive yang intowind.So medicines that emolliate liver and subdue yang should be added while supplementing kidney yin, which is known as the therapy of enriching water to moisten wood.Thus yin-yang theory and the theory of five elements are employed integratedly in traditional Chinese medicine.They can not be divided completely.

It must be noted that to understand human body correctly and thoroughly so as to illustrate life rules can not be limited to yin-yang theory and the theory of five elements. Life rules should be further analyzed through life activities to avoid partial and mechanical employment of yin-yang theory and the theory of five elements, so that they can be interpreted more scientifically.

Questions

1.How to understand the relativity between yin and yang?

2.Try to analyze the pathological changes of human body with yin-yang theory.

3.How to determine treating principles and methods with yin-yang theory?

4.What are the mutual generation and mutual restriction of five elements?And their relations?

5.What are the over-restriction and counter-restriction of five elements?The order between them?And the reasons causing them?