The Yellow Emperor's Classic of Internal Medicine, specifically Chapter 53, explores the principles of acupuncture based on the concepts of fullness and deficiency in the body. Qi Bo, a renowned physician, explains that imbalances, such as having abundant energy yet feeling cold, or low energy with warmth, signify illness. These imbalances are linked to various factors including diet, exposure to weather, and internal conditions. The text details how to diagnose these conditions through pulse and other observations. Finally, it describes acupuncture techniques—opening or closing points with the left hand—for treating fullness and deficiency, respectively, to restore balance.