灵枢经·阴阳清浊 Yin and Yang, the Clear and the Turbid
黄帝曰：余闻十二经脉，以应十二经水者，其五色各异，清浊不同，人之血气若一，应之奈何？歧伯曰：人之血气，苟能若一，则天下为一矣，恶有乱者乎？黄帝曰：余问一人，非问天下之众。歧伯曰：夫一人者，亦有乱气，天下之象，亦有乱人，其合为一耳。
黄帝曰：愿闻人气之清浊。歧伯曰：受谷者浊，受气者清。清者注阴，浊者注阳。浊而清者，上出于咽，清而浊者，则下行。清浊相干，命曰乱气。
黄帝曰：夫阴清而阳浊，浊者有清，清者有浊，清浊别之奈何？歧伯曰：气之大别，清者上注于肺，浊者下走于胃。胃之清气，上出于口；肺之浊气，下注于经，内积于海。
黄帝曰：诸阳皆浊，何阳浊甚乎？歧伯曰：手太阳独受阳之浊，手太阴独受阴之清；其清者上走空窍，其浊者下行诸经。诸阴皆清，足太阴独受其浊。
黄帝曰：治之奈何？歧伯曰：清者其气滑，浊者其气涩，此气之常也。故刺阴者，深而留之；刺阳者，浅而疾之；清浊相干者，以数调之也。
Huangdi said: "I have heard that the twelve channel vessels correspond to the twelve channel-waters of the land, each of which differs in its five colors and its clarity or turbidity. Yet in a person the blood and qi appear to be uniform — how, then, do they correspond to this diversity?" Qibo said: "If the blood and qi of a person were truly uniform throughout, then all under Heaven would be as one — how, then, could there be any disorder?" Huangdi said: "I am asking about a single person, not about the multitudes of all under Heaven." Qibo said: "Even within a single person there is disordered qi, just as within the pattern of all under Heaven there are disordered people — they correspond to one and the same principle."
Huangdi said: "I wish to hear about the clear and turbid aspects of human qi." Qibo said: "That which receives grain is turbid; that which receives breath-qi is clear. The clear pours into yin, and the turbid pours into yang. Of the turbid, that portion which is clear rises to emerge at the throat; of the clear, that portion which is turbid descends and flows downward. When clear and turbid interfere with one another, this is called disordered qi."
Huangdi said: "Now, yin is clear and yang is turbid, yet within the turbid there is a clear portion, and within the clear there is a turbid portion. How does one distinguish the clear from the turbid?" Qibo said: "In the great division of qi, the clear rises to pour into the lung, and the turbid descends to flow into the stomach. The clear qi of the stomach rises to emerge at the mouth; the turbid qi of the lung descends to pour into the channels and accumulates internally in the sea of qi."
Huangdi said: "All the yang channels are turbid — which yang channel is most turbid?" Qibo said: "The Hand Taiyang Small Intestine channel alone receives the turbid portion of yang, while the Hand Taiyin Lung channel alone receives the clear portion of yin. The clear portion rises to travel to the body's open orifices, while the turbid portion descends to travel through the various channels. All the yin channels are clear, yet the Foot Taiyin Spleen channel alone receives a turbid portion."
Huangdi said: "How does one treat this?" Qibo said: "The qi of the clear is smooth-flowing, while the qi of the turbid is rough — this is the constant nature of qi. Thus, in needling yin, one needles deeply and retains the needle; in needling yang, one needles shallowly and withdraws quickly. Where clear and turbid interfere with one another, one regulates according to their proper measure."