Traditional Chinese medicine uses the theories of Yin (feminine) and Yang (masculine) as core principles. Any matter of object can be categorized into yin or yang.
For example, day belongs to yang, night belongs to yin, fire belongs to yang, water belongs to yin, happiness belongs to yang, sadness belongs to Yin.
All of us know that a human being is composed of the human body and the soul. According to yin and yang theory, the human body belongs to yang and the soul/spirit belongs to yin. Diseases can also be categorized into yin or yang diseases.
From a clinical categorization: any disease that comes from a bodily injury, pathological change to the organ, acute infection from a virus and other maladies are catorized as yang diseases, for example a broken leg, a gastric ulcer, the flu and so on. Any disease that is caused by emotional issues such as sadness, anger, fright and other excessive emotions, or any illness relating to a soul or spirit that is damaged or disturbed belongs to yin diseases such as depression, senile dementia, cancer and so on.
Traditional Chinese medicine has provided us the theory that emotions directly related to certain organs. Anger relates to the liver, happiness the heart, worry to the spleen, sadness to the lungs and kidneys with fear. It is easy to find out the physiological changes when people get angry such as shortness of breath, accelerated heartbeat, increased blood flow and red face, at this time most of the blood is pumped to the head in order to support the strong cerebral movements. Meanwhile, the arterial and venous return are imbalanced in the liver because of the exports and emotional changes, the angry energy silts up inside the liver and turns into qi stagnation.
According to the theory of traditional Chinese medicine, qi stagnation causes blood stagnation at this point. At this level the little amount of blood stagnation or qi stagnation does not constitute a health threat. But if a person has the same kind of negative emotion for a long time, then they will increase the qi/blood stagnation in this organ and block the nutrient supply which will cause the organ to become diseased.
Yang diseases are easier to diagnose by western medical equipment, and western medical doctors have an easier time finding the cure for these ailments.
Unfortunatly more than 70% of human diseases belong to the catagory of yin diseases. The causes of these diseases are very complex and some are caused by a combination of different factors. It is difficult to find a clear, single cause of the disease by using modern technology.
For example kidney deficiency, lung deficiency, and stagnation of the liver, spleen wetlands, and other imbalances that are recognized by the traditional Chinese medical system can not be diagnosed by modern medical equipment or chemical examination.
Lots of patients come to me saying "I am in poor physical condition", they dont feel good and they have tried to find out what is wrong from doctors but they can not find out why they are sick, the name of the disease or what caused it. Therefore you need to correctly understand the pathogenesis of a disease to find the cure for the disease.
Every disease or symptom has two sides, yin and yang. The yang side is the symptoms that can be seen by the eyes, diagnosed by equipment, or that can be felt by the patient himself. The yin side is the source or root of the problem, it originates in an organ but you may not relate it with the symptom.
I had a patient whose skin on his whole body was cracking and bleeding frequently, but no doctor could tell him what caused this strange disease before he came to me. According to the theory of Chinese medicine, skin relates to the Lungs, and Spleen controls blood flow. So the yang symptom was the cracking and bleeding skin, and the yin side cause or root of this disease was the Lung and Spleen.