Wuxing which arises from yin-yang refers to the five elements (wood, fire, earth, metal and water) and their different characteristics. It is said that wood arises from water and prevails over earth; fire arises from wood and prevails over metal; earth arises from fire and prevails over water; metal arises from earth and prevails over wood; water arises from metal and prevails over fire.

The five organs of the human body are compared to the five elements and are said to behave likewise:

Liver (wood) complements the heart (fire) and opposes the spleen (earth); the heart complements the spleen and opposes the lungs (metal); the spleen complements the lungs and opposes the kidneys (water); the lungs complement the kidneys and oppose the liver, the kidneys complement the liver and oppose the heart.

Yin-yang wuxing formulates the theory of the jing-luo -- that the human body contains vertical trunks (jing) and branches (luo) made up of 20 invisible passages, 12 meridians (zhengjing) and eight pulses (qijing). They are different from the nervous system known to modern medical students. These passages are divided into two groups: yin and yang. In each group there are six meridians which extend into four limbs and four pulses which are distributed in the body. The internal ones are called yinyang, and the external ones the yang-jing. These meridians and pulses carry a "life force" through the whole body. If the "life force" cannot flow easily in the passages, the body becomes ill. The balance of yin-yang wuxing is essential for peace, harmony and health. Diseases and ailments of the body occur when the balance of yin-yang wuxing is upset. For instance, if the fire element in the heart is too strong for the metal element in the lungs, the physiological balance cannot be maintained. The dominance of heart over lungs can cause the loss of weight, general lassitude, and a pain in the chest. Qigong breathing exercises can help restore the balance.

Since these passages are anatomically invisible, their existence remains a matter of dispute. Although the theory seems to "unscientific", its principles are precise and based on a belief that man has a spiritual as well as a physical existence.

Breathing exercise
Qigong is the Chinese terminology for the system of breathing-control exercises. Literally, qi means "air", which implies a "life force". Gong means an art. Qigong is the art which benefits health and prolongs life.

Qigong is not a religion, it is based on the philosophical principles derived from the theory of yin-yang wuxing in the Book of Changes. In traditional Chinese medicine, yin refers to the tangible body and its blood circulation; yang, the invisible qi and the spirit.

There are three stages in practicing qigong:
1) Deep breathing-control
Qi moves in jing-luo, the passages of meridians and pulses, just as blood flows through blood vessels. The qigong state of deep breathing is similar to fetal breathing in the womb. The fetus cannot breathe externally, it breathes internally and there is a movement of qi.

Breathe gently through the nostrils with mouth shut, so as to put the qi into motion. The aim is to achieve proper control of and the ability to trace qi in your body. To imagine this, think of the movement of qi as follows: First, the qi rises from the baihui point and moves downward past both ears. Next, the divisions of qi meet at the throat and separate again at the naral and go down to the huiyin point. After this, they separate to travel along the collar bones to the chest. They then meet again once more to flow along the inner legs to the feet. Finally, they rush into the ground through the yongquan points.

2) Sitting in meditation
Sit on a stool upright with the baihui and huiyin points on a line and your eyes downwards, imagining they are closed. Imagine there is something over your head at the baihui point, but don't put any force on it. Let it go gently. Hold your legs comfortably, stretch your arms downwards and curve your thumbs and forefingers a little imagining that they are touching one another. Separate the middle, ring and little fingers gently.

There are two steps leading to meditation:
One is to remain calm and collected. This does not mean to stop thinking, but implies making your mind concentrate on only one thing without random thoughts. The other is to achieve total emptiness and calmness. This refers to a higher state of serenity, in which one thinks of nothing.

3) Dantian gong
Apothecaries of antiquity believed that longevity could be enjoyed if pills were prepared in a special way, but others held that the so-called pills of longevity were in reality in the human body. In Chinese, the pill is known as dan. Dantian means the pill region, a region three fingers breadth below the navel in the lower part of the abdomen, located between the bladder and rectum. This area is known as qihai, the sea of air, because all the passages meet there just as all the rivers flow into the sea.

Dantian opens when there is qi and closes when there is none. The qi may descend into it during exhalation. If you are able to deliver qi into dantian through the achievement of breathing-control art, you will be as pure as a piece of white jade and as serene as a lake without a ripple. You will feel as light as a feather and that the qi inside the body is linked with the universe and is limitless as the sea and sky. You will be imbued with a spirit as the rainbow spanning the sky.