The concept of yin-yang was put forth by the Chinese in the sixteenth century in order to help explain what was being observed in the natural world. The Chinese had a penchant for seeing actions, situations, and behaviors as governed by duality. They described this duality as yin and yang.

The two complementary, but opposite philosophies of yin and yang were, and still are, used by the Chinese to interpret such diverse things as the cycle of the year, the growth and death of living things, and health. The principles of yin-yang are broken down into five separate categories; 1)"yin and yang are the fundamental categories of all phenomena 2)“yin and yang are divisible” 3)“yin and yang are rooted in each other” 4)“yin and yang counterbalance each other,” and 5)”yin and yang are mutually convertible." I will describe each of these phases of yin-yang and how they can be applied in Chinese medicine, and in our daily lives.

"Yin and Yang are the fundamental categories of all phenomena." "Yin and Yang are the laws of heaven and earth, the great framework of everything, the parents of change, the root and beginning of life and death..." One can see the beauty of yin-yang in everything. Night is Yin, day is Yang, cold is yin, yang is hot, female is yin, male is yang. I follow cycles of yin and yang in my own life, for example, in the moment of pure birth I was completely yang. When I die I will be totally yin. All life in between can be broken down into either yin or yang; sleeping is yin, activity during the day yang, periods of illness yin, and times of great growth and expansion yang, winter season yin, summer time yang, and so on and so forth.

"Yin and Yang are divisible." Yin and yang can be divided further into yin and yang. Within aspects, there can always be additional partition. This is to say that “each yin and yang phenomena itself possesses both yin and yang aspects that may be further divided in the same way. This process may be carried out ad infinitum.” This is tremendously important in Chinese medicine when looking at pattern differentiation and methods of treatment. For example, the front of the body is yin, the back yang. The front can then be separated into yin and yang with the abdomen being yin and the chest being yang. The various organs in the body have both yin-yang functions, even when considered a predominantly yin or yang organ. For example, the liver is considered a yin organ. It governs movement, which is a yang function, and storing which is a yin function. So, within the zang organ of liver there exists the faculty of both yin and yang.

"Yin and yang are rooted in each other." “Yin and yang are interdependent.” Yin exists because there is yang and vice versa. They depend on one another for definition. One could not speak of temperature if it weren’t for cold (yin) and hot (yang). In Chinese medicine an imbalance of yin will naturally cause a disparity of yang and vice versa. For example, high blood pressure due to excess yang can be caused by an underlying deficiency of yin. The yin keeps the yang rooted.

"Yin and yang counterbalance each other." If yin is excessive, yang will be deficient. If yin is deficient, then yang will be excessive. If there is cold in the body, too much yin, then there is not enough heat, or yang present. If disease is caused by heat it is treated with cold. In my own life I have experienced extreme illness. I believe that this, in part, resulted from a hyperactive lifestyle. I was pushing myself, burning the candle at both ends so to speak. My way of life consisted mostly of yang, lots of activity, and not enough yin, taking time to rest and nurture myself.

"Yin and yang are mutually convertible." In Chinese medicine yin patterns can develop into yang patterns and vice versa. Yin and yang, therefore, transform into one another. An example of this might be someone exhibiting signs and symptoms of an acute attack of hepatitis. This pattern looks very excess, and in Chinese medicine is considered a problem of damp-heat. Nevertheless, this condition can become chronic, budding into cirrhosis of the liver. (Hepatitis B, C, and D all have the possibility of becoming chronic, particularly hepatitis C, even when starting out as acute diseases.) It is also known that in Chinese medicine a deficiency of either kidney yin or yang often causes a lesser deficiency of the other. Or, likewise, patients can exhibit cold-heat conversion, for example someone who is attacked by a wind-cold evil. The cold evil may take up residence in the lungs, showing signs and symptoms of wind-cold which later turn to signs of heat after the phlegm has congealed in the lung.

All in all the classification of yin-yang helps to guide and direct us in our daily lives. It reminds us of where the balance is and how to find it. What a beautiful gift it is to see the contributing qualities of both yin and yang. It is a challenge at times to exist within a world of polarities but it is this struggle that we must choose to learn from. Finding stability within the existing polarities, of yin and yang is like walking a tight rope. If we aren’t paying attention or we seem to lose awareness we risk falling off balance. If we do indeed find ourselves out of sync with our natural surroundings it is not only advisable but detrimental to our health to find our way back to living in support and appreciation of yin and yang.