《黄帝内经·素问·离合真邪论》
《针经》上说的气之盛衰，左右偏胜，取上以调下，去左以调右，有余不足，在荥输之间进行补泻，我亦懂得了。
经言气之盛衰，左右倾移，以上调下，以左调右，有余不足，补泻于荣、输，余知之矣。
The classic of Acupuncture says that when qi decays and flourishes, and when the left or right meridians are dominant, needling is performed at the upper part to regulate the lower and at the left to regulate the right. I have understood that if needling is performed on the part of the meridian where qi and blood are abundant to supplement and on the part of the meridian where qi and blood are deficient to drain, 