In traditional Chinese medicine, or symptomatic diagnosis, are based on the philosophy of this principle. The two forces that control the running of the universe. Yin represents our feminine nature, encompassing darkness, tranquility, expansion, depth, cold, and wetness. The moon and water are yin elements.

Yang represents our masculine nature, encompassing light, activity, light, contraction, part, and dryness. The heaven the sun and fire are yang elements. We have 14 main body meridians 12 paired meridians and two-vessel meridians.

Meridian pairs complement each other. One is yin energy flowing up the body, and one is yang energy flowing down the body, six yin, six yang and two-vessel meridians which are both yin and yang.