Yin and Yang
The Formation of the Theory of Yin
and Yang
Yin and yang was originally included in the category of the ancient
philosophy of China. At first, yin and yang meant whether a place faces the sun
or not. The place being exposed to the sun is yang, whereas the place not having
a southern exposure is yin. The southern side of a mountain, for example, is yang,
while the northern side of it is yin subsequently, through long-term living, practice
and observation of every kind of natural phenomenon, people have come to realize
that yin and yang, the two components which oppose each other, exist in all things,
and that, furthermore, their interaction promotes the occurrence, development
and transformation of things. In consequence yin and yang is used as the means
of reasoning things out in analyzing all the phenomena in the natural world. "Lao
Zi", a philosophical work written in ancient China, says: "All things
on earth carry yin on their backs and hold yang in their arms." That is,
each thing contains the two components of yin and yang. "Zhou yi", also
an ancient philosophical work, draws from the complicated natural and social phenomena
the same two philosophical concepts, yin and yang, whose symbols are (- -) and
(-), and advocates yin and yang as the "Dao" (the basic law in the natural
world) of the heaven and earth, that is, to consider the transformation of yin
and yang into each other as the basic law in the universe. The impact of yin and
yang theory on the science of traditioanal Chinese medicine (TCM) has promoted
the formation and development of TCM's own theoretical system and, finally it,
itself, becomes an important component part of the classic theory of TCM.
The
Content of the Theory of Yin and Yang
The content of the theory of yin and
yang can be described briefly as follows: opposition, interdependence, relative
waxing and waning, and transformation.
1) Opposition and Interdependence of
Yin and Yang
By the opposition of yin and yang, we mean all things and phenomena
in the natural world contain the two opposite components. For example, the heaven
and earth, outside and in-side, movement and stability, coming in and going out,
day and night, cold and heat, rising and falling, etc., all these are opposites.
In the theory of yin and yang, the heaven is considered as yang, while the earth
is yin; outside is yang, while inside is yang; movement is yang, while stability
is yin; going out is yang while coming in is yin; day is yang, while night is
yin; heat is yang, while cold is yin; rising is yang, while falling is yin; rapid
pulse is yang, while slow pulse is yin. These opposite pairs show that yin and
yang exist within all things and phenomena. yin and yang not only oppose but also
contain each other, without the other, neither can exist. For instance, there
would be no earth without heaven1 and vice versa. Without outside, there would
be no inside, and vice versa. This relationship of coexistence is known as interdepencence.
TCM holds that "functional movement" belongs to yang, "nourishing
substance" to yin, and that the one can not exist without the other; for
example, if the intestines and other internal organs do not move, "nourishing
substance" can not be digested or absorbed; and if over a long period "nourishing
substances" are not provided, the organs cease to move. The book, Canon of
Medicine (722-221 B.C.), says: "yin in the interior is the guardian of yang,
yang in the exterior is the activator of yin". This also shows the relationship
of interdependence between yin and yang.
2) The Waxing and Waning of Yin and
Yang, and the Transformation between Yin and Yang
What is meant by the waxing
and waning of yin and yang? Yin and yang opposing each other and yet depending
on each other for existence, are not stagnant but in a dynamic state, i.e., while
yin wanes, yang waxes, and vice versa. This dynamic change of succeeding each
other between yin and yang is known as the waxing and waning of yin and yang.
Take the seasonal climatic variations in the natural world for example. The weather
gets warm when winter gives way to spring, and hot when spring gives way to summer,
during which time yin wanes, while yang waxes. However, it gets cool when autumn
replaces summer, and cold when winter replaces autumn in which time yang wanes,
but yin waxes.
By "transformation" we mean yin and yang will transform
into each other under certain conditions. For instance, in the course of suffering
from a disease, the patient runs a high fever, has a red complexion, feels irritable
and restless, and gets into a rapid and strong pulse condition. But all of a sudden,
he feels listless, his temperature becomes lower, his face turns pale, and his
pulse condition becomes so fine that the pulse is almost cut off. This is an example
of transformation between yin and yang. The general law according to which things
are distinguished into yin or yang is as follows. All that are hyperfunctional,
excited, hot, moving, strong, bright, invisible. Light and clear, up and upwards,
out and outwards, and all that have active specific characteristics belong to
yang. On the contrary, all that are waning, restricted, cold, weak, dark, visible,
heavy and turbid, down and downwards, in and inwards and all that have inactive
specific characteristics belong to yin. It should be pointed out that the yin
or yang property of things is not absolute but relative. This relativity of yin
and yang is shown in the intertransformation between yin and yang mentioned above,
i.e., yin may transform into yang and vice versa; it is also shown in the constant
divisibility of yin and yang, i.e., either yin or yang can be still divided into
another pair of yin and yang. For instance, day is of yang nature and night is
of yin nature, but both day and night can be again divided like this: the period
from dawn till noon is the yang aspect of yang; the period from noon till dusk
is the yin aspect of yang; the period from dusk till midnight is the yin aspect
of yin; the period from midnight till dawn is the yang aspect of yin.
Uses
of the Theory of Yin and Yang in TCM
Yin and yang is embodied in every aspect
of TCM's theoretical system. It is used to explain the tissues and structures,
physiology and pathology of the human body, and direct clinical diagnosis and
treatment.
1) Using Yin and Yang to Explain the Tissues and Structures of
the Human Body
According to the theory of yin and yang, it is considered that
opposite but unitive phenomena between yin and yang exist between rostral and
caudal, inside and outside, exterior and interior, dorsal and ventral aspects
of every tissue and structure of the human body. When speaking of yin and yang
in the human body, the upper part is yang, the lower part yin; the exterior is
yang, the interior yin; the back is yang, the abdomen yin; the lateral aspect
of the extremities is yang; the medial aspect yin. When speaking of yin and yang
of the internal organs in the body, the five viscera, i.e., the heart, liver,
spleen, lung and kidney, are yin, because their functions of preserving vital
substance tend to be stable; the six bowels organs, i.e., the gallbladder, stomach,
large intestine, small intestine, urinary bladder and triple warmer, are yang,
because their functions of transmit-ting and digesting water and food tend to
be active. The relationship between yin and yang also remains constant among the
five viscera. The heart and lung are yang, because of being higher, while the
liver, spleen and kidney are yin, because of being lower. When speaking of yin
and yang of every organ, the function is yang, the substance yin. When speaking
of yin and yang of the channels and collaterals, the channels may be divided into
channels belonging to yin and channels belonging to yang. Collaterals can also
be classified as yin collaterals and yang collaterals. When speaking of yin and
yang of the twelve channels, three are yang channels of the hand and three yin
channel of the hand, three yang channels of the foot and three yin channels of
the foot. As to the vital energy and blood, vital energy (qi) is yang, blood yin.
2) Using Yin and Yang to Explain the Physiological Function of the Human Body
TCM
believes that the normal physiological functions of the human body result from
the opposite, unitive and coordinate relation between yang (function) and yin
(substance). Yin and yang are always in the state of dynamic balance. It is known
as yin is even and well while yang is firm, hence a relative equilibrium is maintained
and health is guaranteed". Physiological function is based on substance.
Without substance, including the essence of life, blood, constructive energy and
body fluid, there would be no source for functions. But the metabolism of substance
must depend on the performance of function. If yin and yang of the human body
separate from each other and can not aid each other, life will come to an end.
This is what is called, in TCM, "the divorce of yin and yang means the end
of one's life."
3) Using Yin and Yang to Explain the Pathological Changes
of the Human Body
In TCM, it is thought that the imbalance of yin and yang
is one of the basic pathogeneses of a disease. For example, preponderance of yang
leads to hyperfunction of the organism and heat manifestations, while preponderance
of yin hypofunction of the organism or endogenous cold. Deficiency of yang brings
on symptoms of external cold, while deficiency of yin as the result of exhausted
vital essence leads to endogenous heat. Yang in excess makes yin suffer, while
yin in excess makes yang suffer. In severe damage of yang, yin is involved, in
severe damage of yin, yang is involved, too. Thus, yin and yang are both damaged.
A case of yin nature (hypofunction) in its extreme may show yang (hyperfunction)
symptoms and signs, while a case of yang nature (hyperfunction) in its extreme
will give rise to yin (hypo-function) symptoms and signs.
4) Using Yin and
Yang to Diagnose and Treat Diseases
Because one of the basic pathogeneses of
a disease is the imbalance of yin and yang, any disease, no matter how intricate
and volatile its clinical manifestations, can be diagnosed with the theory of
yin and yang. Although diseases are classified as exterior and interior according
to their locations, and as cold, heat, asthenia and sthenia according to their
nature, if the theory of yin and yang is used, the types of exterior, heat and
sthenia are yang; interior, cold and asthenia yin. In TCM, in making a diagnosis,
the first important thing is to ascertain whether the disease is yin or yang.
For example in observation of the patients' complexion, those who look bright
are patients of the yang character, while those who look dark and gloomy are patients
of the yin character. In listening and smelling, those who have a loud and clear
voice have a yang character, while those who have a low and weak voice a yin character.
In inquiring, those who have a fever, feel thirsty, suffer from constipation and
have a rapid pulse condition are of yang, while those who have an aversion to
cold, don't feel thirsty, have loose stools and a slow pulse condition are of
yin. In pulse feeling and palpation, those whose pulses are floating, rapid, large,
slippery and full are of yang, while those whose pulses are deep, slow, small,
rough and empty are of yin. How is the theory of yin and yang used in treating
diseases in TCM? Preponderance of yang leads to hyperfunction of the organism
and heat manifestations, which is known as sthenic heat syndrome. In treating
sthenic heat syndrome, drugs of cold and cool nature should be used in order to
inhibit the preponderance of yang, i.e., heat syndrome must be treated with drugs
cold in nature. Preponderance of yin leads to hypofunction of the organism or
endogenous cold that is called cold-sthenia syndrome. In treating it, drugs of
a warm-heat nature should be used so as to restrict the predominance of yin, i.e.,
cold syndrome should be treated with drugs warm in property. The deficiency of
yang brings on symptoms of external cold, which are called deficiency-cold syndrome.
In treating it, drugs of warm and invigorating nature should be used. This is
known as treating the hyperactivity of yin by supplementing yang, the source of
fire. The deficiency of yin as a result of exhausted vital essence leads to endogenous
heat, which is called as asthenic heat syndrome. In treating it drugs of nourishing
yin should be used. Thi5 is what is known, in TCM, as replenishing the vital essence,
(especially that of the kidney and liver) to check virtual yang (exuberance of
the vital function) caused by the deficiency of yin factor. In treating those
diseases in which there is severe damage of yang, yin is involved, although the
first thing is to reinforce the vital function, yet, the vital essence, at the
same time, should be also invigorated. In treating those diseases in which there
is severe damage of yin, yang is involved, while the vital essence is being replenished,
the vital function should be strengthened, too. In treating those diseases resulting
from the deficiency of both yin and yang, both the vital essence and the vital
function should be replenished. The property, flavor and function of Chinese medicinal
herbs can also be summarized in the light of the yin and yang theory, and this
forms a basis for the clinical application of Chinese medicinal herbs. For example,
the herbs of cold and cool nature belong to yin; while the herbs warm and hot
in nature, yang. The herbs with sour, bitter and salty flavors belong to yin,
while the herbs with pungent, sweet and bland flavors, yang. The herbs with astringent
and subsiding function belong to yin, while the herbs with dispersing, ascending
and floating function, yang. In TCM, the principles of treatment are established
just on the basis of the predominance or weakness of yin and yang. Once the principle
is established, herbs are selected according to their property of yin and yang
and their function. In so doing, one can achieve the aim of curing diseases.
Extracted
from "Basic Theory of Traditional Chinese Medicine"