Yin and Yang
The concepts of yin and yang are integral to the discussion of Oriental medicine theory, diagnosis, and treatment. They express a dynamic system of relationships, patterns and functions. According to this philosophy, all phenomena consist of these two opposing, yet complementary forces that work together to maintain balance. The movements and changes of yin and yang can be seen in all aspects of our lives as well as in the environment around us.
Yin is described as the opposite of yang and corresponds to the passive, dark, receptive, cool, and moist principles. It is most dominant at night and its directional movement is downward and inward. In the environment, this energy is expressed in the roots of plants and their ability to take nourishment from the ground. It is embodied in water, the winter season, the hibernation of animals and dormancy of plants. Yin is the tendency to slow down, to go inward and to reflect, and in the 24-hour cycle represents the quiet, peaceful qualities of nighttime.
Yang is the opposite of yin and is represented by the active, light, warm, dry and creative principles. It is most dominant during the day and its directional movement is outward and upward. In the environment, this energy is expressed by the warmth of the sun, growth of plants above the ground, and creative movement. The yang is said to rise in the spring and is at its height in the summer. It is the tendency to activity, to go outward and create, and in the 24-hour cycle represents the dynamic, bright qualities of daytime.
Nothing is completely yin or yang as everything contains both tendencies. Yin and yang both embody and constantly transform into each other, as night into day, and winter into spring and summer. For example, day is yang and night is yin but they cannot actually be separated as one leads naturally to the other in the 24-hour cycle. Humans and all life maintain active phases (yang) that are balanced by times of rest (yin). Within the yang energy of the day, there is shade (yin), and within the yin energy of the night, there are stars (yang). This interdependent relationship is reflected in the universal symbol of yin-yang, which represents a dynamic equilibrium between the two principles and the interplay of each within the other.
Our health also reflects the relative balance or imbalance of yin and yang. When the flow of qi is insufficient, unbalanced or interrupted, yin and yang become unbalanced, and illness may occur. According to the Su Wen (“Yellow Emperor’s Inner Classic Questions and Answers”), "When yin keeps balance with yang and both maintain a normal condition of qi, then health will be high-spirited. A separation of yin and yang will lead to the exhaustion of essential qi." Health and well-being include a balance between the mind and body, between activity and rest, and in outward action and inward reflection.