“The yang qi of the body is like the Sun. If the Sun loses its brilliance, all things on Earth become inactive. The Sun is the ultimate yang. This heavenly energy of the Sun surrounds the Earth. And in the body, this means that the yang qi circulates around the center or core and has the function of protecting the body.
Huang Di continued, “Living in a cold climate, one must take care with one’s activities. Just as people indoors are protected from the weather, the yang qi acts as the walls in a house to protect the body. It is important to be aware, and not allow any openings; pathogenic energy cannot invade if the castle doors are closed.” -The Yellow Emperor’s Classic
“The key to mastering health is to regulate the yin and the yang of the body. If the yin and yang balance is disrupted, it is like going through a year with Spring but no Winter, or Winter but no Summer. When the yang is excessive and cannot contain itself, the yin will become consumed. Only when yin remains calm and harmonious will the yang qi be contained and not be overly expansive. The spirit will be normal and the mind clear. If the yin and yang separate, the jing/essence and the shen/spirit will also leave each other.
“The source and preservation of yin come from the five flavors of food in the diet, but improper use of the five flavors may also injure the five zang organs. Too much sour taste may cause overactivity of the Liver and underactivity of the Spleen. Too much salty taste can weaken the bones and muscles, and stagnate the Heart qi. Too much sweet taste can disturb the Heart qi, causing it to become restless and congested, as well as cause imbalance in the Kidney energy. Too much bitter taste disrupts the Spleen’s ability to transform and transport food, and causes the Stomach to digest poorly, and swell.
“Therefore, one should be mindful of what one consumes to insure proper growth, reproduction, and development of bones, tendons, ligaments, and meridians of acupuncture. This will help generate the smooth flow of qi and blood, enabling one to live to a ripe age.” -The Yellow Emperor’s Classic on Internal Medicine