Theory of yin yang helps define the inner functioning of nature, and it provides clarification of why there are night and day, light and dark, good and evil, right and wrong, male and female, etc.
The two energies of yin and yang are of direct opposites and so one feed the other the energy it lacks. It is through this interchange that they convert from the inside out and become each other, creating the continually repeated cycle from life to death to life again.
Yin & Yang Symbol
Meaning of yin and yang in Chinese are bright and dark sides of an object. Traditional Chinese uses yin and yang to represent a wider range of opposite properties in the universe: they are cold and hot, slow and fast, low and high, male and female, right and wrong, etc.
Yang
In general, Yang has characterized as anything that is moving, ascending, bright, progressing, and hyperactive, including functional disease of the body, pertains to yang.
Yin
In general, Yin has characterizing as anything with stillness, descending, darkness, degeneration, hypo-activity, including organic disease, are all pertain to yin.
Functioning of Yin-Yang
The functioning of yin and yang is guiding by the law of unity of the opposites or conflicting, but at the same time mutually dependent. The nature of yin and yang is coexistence means neither being able to exist in isolation. Without "cold" there would be no "hot"; without "moving" there would be no "still"; without "dark,” there would be no "light."
Opposites in all objects and phenomena are in continuous motion and change: The growth and advance of the one mean the decline and retreat of the other.
For example; day is yang and night is yin, but morning is considering as being yang within yang, afternoon is yin within yang, evening and before midnight is yin within yin and the time after midnight and before morning is yang within yin.
Yin-Yang balance and imbalance effects
TCM considers human life as a physiological process in constant motion and change. At normal conditions, the increase and decrease of yin and yang are keeping within a certain range, reflecting a dynamic equilibrium of the physiological processes. When the balance is affected or disturbed, disease develops.
Typical disease causing yin-yang imbalances include; excess of yin, excess of yang, deficiency of yin, and deficiency of yang.