Discussion on Taiyin and Yangming

Yellow Emperor asked: Taiyin and Yangming are interior-exteriorly related, corresponding to the spleen and stomach channels, yet their diseases differ—why is that? Qi Bo replied: The pathways of yin and yang channels are different; there are alternating changes of deficiency and excess, opposite tendencies of favorable and unfavorable directions, some diseases arise from the interior, and some are contracted from the exterior. The sources of disease are different, so the names of the diseases also differ.

Yellow Emperor said: I wish to hear about their different symptoms. Qi Bo said: Yang channels correspond to heavenly qi and govern the exterior; yin channels correspond to earthly qi and govern the interior. Thus, the yang pathway is replete, and the yin pathway is vacuous. Therefore, when encountering external deficient pathogenic factors and thieves of wind, the yang channels are easily affected; when there is no moderation in diet or regularity in daily life, the yin channels are easily affected. When yang channels are affected by pathogens, they transmit into the six bowels; when yin channels are affected by pathogens, they transmit into the five viscera. When pathogens transmit into the six bowels, there will be fever in the body, inability to sleep at proper times, and in the upper part, wheezing and rapid breathing; when pathogens transmit into the five viscera, there will be abdominal fullness and obstruction, and in the lower part, diarrhea with undigested food, which over time becomes dysentery. Thus, the throat governs heavenly qi, and the pharynx governs earthly qi. Therefore, yang channels are easily affected by wind pathogens, and yin channels are easily affected by dampness pathogens. Qi of yin channels ascends from the feet to the head, then descends along the arms to the fingertips; qi of yang channels ascends from the hands to the head, then descends to the feet. Hence it is said: In diseases of yang channels, when qi ascends to its extreme, it will descend; in diseases of yin channels, when qi descends to its extreme, it will ascend. Therefore, when injured by wind pathogens, the upper body is affected first; when injured by dampness pathogens, the lower body is affected first.

Yellow Emperor asked: When the spleen has disease, the four limbs cannot function normally—why is that? Qi Bo said: The four limbs all receive qi from the stomach, but the qi cannot directly reach the channels; it must rely on the spleen's transportation to receive the essence. Now, when the spleen has disease, it cannot transport fluids to the stomach, the four limbs cannot obtain nourishment from the essence of water and grain, qi daily weakens, the channels do not flow smoothly, and the sinews, bones, and muscles have no qi to grow, so they cannot function normally.

Yellow Emperor asked: The spleen does not exclusively govern a single season—why is that? Qi Bo said: The spleen corresponds to earth in the five phases, governs the center, and constantly oversees the qi of the four viscera during the four seasons, dwelling and governing in the last eighteen days of each season, so it cannot exclusively govern a complete season. The spleen constantly stores the essence of the stomach's earth, and earth can nurture all things, emulating heaven and earth, so its qi spreads throughout the upper and lower parts, reaching the head and feet, and cannot be limited to governing a single season.

Yellow Emperor asked: The spleen and stomach are connected only by a single membrane, yet the spleen can transport fluids for the stomach—why is that? Qi Bo said: The Foot Taiyin channel is the three yin channel; its channel runs through the stomach, connects to the spleen, and links with the throat, so the Taiyin channel can transport the essence of the stomach to the three yin channels. The Yangming channel is the exterior and the gathering place of nourishment for the five viscera and six bowels, and it also transports the essence of the stomach to the three yang channels. The five viscera and six bowels each obtain essence from the Yangming channel through their own channels, so the spleen can transport fluids for the stomach. If the four limbs cannot obtain the essence of water and grain, they daily become weaker, the yin channels do not flow smoothly, and the sinews, bones, and muscles have no qi to grow, so they cannot function normally.