Understanding the concept of Yin and Yang is crucial to understanding the tenets of
traditional Chinese medicine. All disorders, at their most basic, can be broken down
to show an imbalance of Yin and Yang, and all our treatments are fundamentally efforts
to regain their equilibrium. The concept, while extremely simple, is yet quite profound.
Yin/Yang theory starts with the notion that all things in the universe can be divided into
a Yin portion and a Yang portion. It continues to state that each of those portions is
itself infinitely divisible into smaller and smaller partitions of Yin and Yang. There
is nothing that is entirely Yin in character nor anything that is entirely Yang; they
only exist in relation to one another. The most easily understood example of this is
the no-darkness-without-light scenario. (Quantum physicists just love this sort of thing.)
Yin and Yang are represented graphically by the tai ji symbol, shown below. In it,
two separate but equal halves— black for Yin, white for Yang—swirl around each
other and transform into one another, with each containing a kernel of the other at heart.
TCM theory states that Yin and Yang are inseparable in life—we cannot have night without
day, cold without hot, movement without stillness, etc—and when each remains in balance
with the other, harmony prevails and we remain healthy. In human terms, Yin and Yang separate
only at the moment we die, and even then the universal balance is maintained. All things
remain in flux, yet and all things remain the same. (The theory of Yin and Yang applies
to much more than just our health, but for the sake of this forum, we'll focus on its medicinal
The upper half of the body is Yang compared to the lower half. The back of
the body is Yang compared to the front. The scalp is Yang compared to the face.
The extremities are Yang compared to the torso. You get an idea of the infinite
divisibility of each body into Yin and Yang aspects. This is also true in nature.
For example, water is Yin compared to fire but Yang compared to mountains.
The difference is in how we look at them. Water is cool while fire is hot, but
water flows while mountains are still.
These analogies are also seen in the homeostatic functioning of our bodies. Fire
represents the flame that keeps us alive and stokes all our metabolic processes.
Water in turn represents the cooling, nourishing aspects of our systems. Kidney
Fire (in the form of Yang Qi) warms the Spleen, which in turn is able to transform
our food into useable Food Qi. (Without that Yang Fire, our digestive system would
be like using a rice-cooker that's not plugged in … you can wait all day, but the
hard rice you have in the pot isn't going to cook.) The Lungs receive the "mist"
from the cook-pot Spleen and in turn rain that mist down to the Kidneys, which are
thus kept cool (tempering the Yang Fire). Likewise, the Fire of the Heart assists in
our mental and emotional functioning, but, lest we get too "hot headed," our Kidney Yin
keeps the Heart Fire in check. Yin and Yang thus maintain harmony and our bodies remain
Yin and Yang become imbalanced in a variety of ways, sometimes with a true
excess or deficiency of one over to the other, other times with a relative
excess or deficiency. One example of a true excess of Yang over Yin is a
raging fever (redness and heat belong to Yang) from an acute flu or infection in
an otherwise healthy person. The person's store of nourishing, cooling Yin
fluids has not yet been damaged by the high fever, which has just begun; thus,
the overall state of the Yin remains unchanged although the Yang blazes (normal
Yin, excessive Yang). In this case, the treatment principle would likely be to sedate
the Yang, rather than to nourish the Yin. The goal of treatment would be to bring the
person back to equilibrium before strengthening their immune system to prevent future attacks.
An example of a relative excess of Yang over Yin is the low-grade fever and night
sweats associated with menopause. Over the course of a woman's life, she may consume her
Yin in ways both natural (childbearing, menstrual bleeding) and unnatural (relating
to her lifestyle, such as smoking, over-consumption of spicy foods, not getting enough sleep).
In this state, even if her Yang is at normal levels, her deficient Yin will show up as Heat,
or a relative excess of Yang. In this case, the treatment principle would likely be to
nourish the Yin, which is deficient, rather than sedating the Yang, which remains at
If the first patient's fever were allowed to burn uncontrolled, Yang would eventually
overpower and consume Yin. Under the most extreme conditions, when Yang is allowed to
entirely consume Yin, death (in this case by dehydration) will result, as one cannot
exist without the other. The same would also prove true in the case of prolonged
exposure to extreme cold, where Yin (cold weather) would eventually overpower Yang
(a body's natural warmth) and lead to their "separation," death.