Yin–Yang: Clear and Turbid
The Yellow Emperor asked: I have heard that the twelve regular channels correspond to the twelve rivers. The five colors they manifest are each different, and there are also distinctions between clear and turbid. Yet if the qi and blood in humans were the same, how would they correspond? Qi Bo replied: If the qi and blood in humans could truly be completely identical, then the whole world would become one body—how could there be any disorder? The Yellow Emperor said: I am asking about the conditions within a single person, not about the many people of the world. Qi Bo said: Even within a single person there is disordered qi, just as among the world’s people there are disordered individuals; the principle behind these two is actually one and the same.
The Yellow Emperor said: I wish to hear about the clear and turbid conditions of the qi in the human body. Qi Bo said: The qi that receives the essence of water and grain is turbid; the qi that receives the qi of nature is clear. Clear qi flows into the yin aspect, turbid qi flows into the yang aspect. Qi that is turbid yet contains clarity rises upward and exits through the throat; qi that is clear yet contains turbidity moves downward. When clear and turbid interfere with each other, it is called chaotic qi.
The Yellow Emperor said: The qi of the yin aspect is clear, and the qi of the yang aspect is turbid. Yet within turbid qi there is clear qi, and within clear qi there is turbid qi—how should clear and turbid be distinguished? Qi Bo said: In the general separation of qi, clear qi ascends and pours into the lung, while turbid qi descends and moves to the stomach. The clear qi from the stomach exits upward through the mouth; the turbid qi from the lung descends and pours into the channels, accumulating internally in the sea of qi.
The Yellow Emperor said: All the yang channels receive turbid qi—which yang channel receives the heaviest turbid qi? Qi Bo said: The Hand Greater Yang Small Intestine channel alone receives the turbid qi of the yang aspect; the Hand Greater Yin Lung channel alone receives the clear qi of the yin aspect. Clear qi moves upward to the orifices; turbid qi moves downward to the various channels. All the yin channels receive clear qi, but the Foot Greater Yin Spleen channel alone receives the turbid qi within it.
The Yellow Emperor said: How is this treated? Qi Bo said: The characteristic of clear qi is smoothness; the characteristic of turbid qi is roughness—this is the normal pattern of qi. Therefore, when needling the yin channels, insert deeply and retain the needle; when needling the yang channels, insert shallowly and withdraw the needle quickly. When clear and turbid interfere with each other, regulate according to the specific condition.