Interaction Between Yin and Yang
The theory of yin and yang holds that all things stem from the interaction between yin and yang, which is the root for the emergence and variation of myriad things. In nature, the generation and transformation of all things are caused by the communication between the heavenly yang qi and earthly yin qi; the descent of heavenly yang qi and the ascent of earthly yin qi provide the prerequisite for such a change. In other words, the interaction of the physical and chemical factors between the heaven and earth gives rise to all things in nature, and without such an interaction, there would be no generation and transformation of myriad things on earth. As far as the human beings are concerned, the intercourse between man and woman give birth to new lives, and the sustaining of life also relies on the inter- communication between his or her own yin and yang. If yin and yang are separated or insolated, life will be terminated, too.
The interaction between yin and yang is the precondition for the generation and transformation of all things. For this reason, TCM stressed that different components of the body interact constantly, and so do the physiological functions. This ensures the normal proceeding of life activi- ties. For instance, the mutual interaction of yin, qi and yang qi leads to normal physiological functions whereas disorders of such an interaction may give rise to a series of pathological manifestations.
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Interaction between yin and yang is carried out incessantly. It may be manifested as mutual restriction, interdependence, mutual waning and waxing, inter-transformation and inter-preponderance, etc. That is to say, all these manifestations take place in the process of yin-yang interaction.
Mutual Restriction Between Yin and Yang
The theory of yin and yang holds that all things in nature have two aspects: yin and yang. They are mutually contradictory in nature and mutually restricted in relation. Such a relationship, called yin and yang in opposition ancient philosophers, can be exemplified by the opposite aspects of up and down, left and right, motion and stillness, exiting and entering, ascent and descent, darkness and brightness, day and night, cold and heat, or water and fire, etc. Take the seasonal variation as an example. In spring and summer it is warm and hot because the yang-heat qi becomes gradually predominant, suppressing the cool and cold qi of the autumn and winter; In autumn and winter it is cool and cold because the yin-cold qi becomes gradually predominant, suppressing the warm and hot qi of the spring and summer. From the Winter Solstice to the Beginning of Spring, yang qi waxes gradually while yin qi wanes accordingly. Yang qi reaches its prime in summer when yin qi hides inside. From the Summer Solstice to the Beginning of Autumn, yin qi waxes gradually while yang qi wanes accordingly. Yin qi reaches it prime in winter when yang qi hides inside. In such a cycle yang qi and yin qi wax and wane year in and year out. This is how the seasonal cycle of warm spring, hot sum- mer, cool autumn and cold winter is explained by the relationship of mutual opposition and restriction between yin and yang.
The two opposite aspects of yin and yang are inter-restricted, so exces- sive exuberance of one side will inevitably lead to relative insufficiency of the other side. On the contrary, excessive debilitation of one side may also result in the relative hyperactivity of the opposite side. Such a change must be controlled within certain limits so as to maintain its relative dynamic equilibrium. If it gets out of control, the balance between yin and yang will be broken, causing relative exuberance or debilitation of yin and yang which points to the occurrence of diseases.
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Daily Exercises
1. What are the initial connotations of yin and yang? 2. What are the attributes of yin and yang?
3. Why yin and yang are mutually opposite in nature? 4. Why yin and yang are mutually restricted in relationship?
The Essentials of Yin-Yang Theory
The interdependence and inter-promotion of yin and yang
Yin and yang are a unity of opposites. They are opposed to and, at the same time, depend on each other. Neither can exist in isolation. In other words, without yin there would be no yang, without the upper there would be no lower, and without cold there would be no heat, and vice versa. All of these indicate that yin and yang are inter-rooted, and the survival of one side relies on the existence of the other. Such a relation of interdependence is called inter-promotion between yin and yang by the ancient philoso- phers. On the basis of yin-yang interdependence, they are also inter-pro- moted and mutually reinforced. For instance, the ascent of earth-qi pertains to yang while the descent of heaven-rain to yin; water vapor rises with earth- qi and forms could, which is prerequisite to the descent of rain and this, in turn, may provide the preconditions for the re-ascent of earth- qi by replenishing the water-vapor on the ground. Substance pertains to yin whereas function to yang. They are inter-depended and inter-promoted for the reason that functional activities are the result of material move- ments while the composition of substance relies on the functional activi- ties. Neither of them can exist in isolation.
Yin and yang depends on each other. Without yin, there would be no yang, and vice versa. If this relation is disrupted, it will lead to such a mor- bid condition described by the ancients as “solitary yin cannot generate and solitary yang cannot grow.” When it comes to the human body, diseases may be induced or even life activities will be terminated as a result.
Waning-Waxing of Yin and Yang in a Balance
The inter-restriction, inter-dependence and inter-promotion between yin and yang are not invariable but in constant motion and change. This is
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called waxing-waning or balance of yin and yang. Such a balance is nei- ther static nor absolute, but a relative equilibrium in which one waxes while the other wanes. This is completely consistent with the laws of motion which hold that movement is absolute while quiescence is relative, and waxing-waning is absolute while balance is relative. In other words, the absolute movement and relative quiescence do not preclude each other, nor do the absolute waxing-waning and relative balance contradict each other. In such a process, a myriad of things germinate, grow, and thrive constantly on earth. For example, seasonal variation from winter to spring and then to summer is a process of yin waning and yang waxing, with the weather turning from cold to warm and then to hot, whereas from summer to autumn and then to winter is a process of yang waning and yin waxing, with the weather turning from hot to cool and then to cold. The seasonal variations and weather changes, marked by either yin waning and yang waxing or yin waxing or yang waning, are in a relative and dynamic balance when viewed from the perspective of the climatic changes of the whole year.
Despite that waxing-waning is absolute and balance is relative, the importance and necessity of relative balance can never be neglected. Only through the synthetic action of both can things develop normally and may the human body maintain its proper life activities. If this relationship goes to extremes or beyond certain limits, the relative balance of yin and yang will be broken, leading to the relative exuberance or debilitation of yin and yang or the morbid waxing and waning of yin and yang.
Inter-Transformation Between Yin and Yang
This refers to the transformation of yin or yang into its opposite side under certain circumstances, namely yin transforming into yang or yang trans- forming into yin. It is an alternation of the overall attribute of yin or yang of things. Each thing is either yin or yang in nature, which is determined by whether yin or yang is in predominance. However, such a relation is not invariable, but in constant change which, beyond certain limits, may cause the change of things in nature from yin to yang or yang to yin. Hence, the alternation often occurs when it goes to extremes, which is known as “things always reverse their nature after reaching an extreme.”
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Take the seasonal variation again, when the climate changes from warm spring to hot summer, the trend will be reversed, as is signified by the appearance of cool autumn; and when cool autumn turns to cold winter, the weather may become warm again with the appearance of spring. Such a fundamental change will not occur if it does not go to extremes. So it is said in Su Wen (Plain Conversation, 素问) that “extreme cold produces heat, and extreme heat produces cold” and “extreme yin turns to yang, extreme yang turns to yin.” Only when the development goes to extremes can fundamental change occur. This is also true for the alternation of day and night and the changes of weather in nature. In Su Wen, the ascent or descent of the heavenly qi and earthly qi is also indicative of the inter- transformation between yin and yang.
Many ancient philosophers have penetrating remarks on this point. For instance, Lao Zi said in Dao De Jing (Classic of the Virtue of the Tao) that fortune and misfortune go hand in hand, which clearly points out the fact that fortune and misfortune are mutually transformed. In Su Wen, it is indicated that life and death are inter-connected, and negative factors are contained in fresh things while positive factors are conceived in perishing things. All these transformations are realized through the process of con- stant motion, or incessant waning and waxing of yin and yang. In this sense, it is safe to say that interdependence between yin and yang is the intrinsic cause responsible for such a transformation while waxing and waning of yin and yang provides the essential conditions.
In conclusion, yin or yang is the relative attribute of things and can be subdivided infinitely. The inter-restriction, inter-dependence, inter-pro- motion, and inter-transformation of yin and yang are an illustration of the interaction between yin and yang which is not solitary and static, but inter- connected, inter-restricted and inter-produced. A good understanding of these basic points is helpful for the application of yin-yang theory in the practice of TCM.
Daily Exercises
1. What are inter-dependence and inter-promotion of yin and yang? 2. What are waxing-waning balance between yin and yang?
3. What is inter-transformation between yin and yang?
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