Phlegm is a product of the body's activities acting upon qi and moisture taken in with food and beverages; it is "congealed moisture." Unlike qi, phlegm is always viewed by Chinese physicians as substantive and stagnating rather than light and flowing, though there are two kinds of phlegm: the visible, which has greater accumulation of matter, and the invisible, which is finely divided, though not as fine as qi. Phlegm is, in some ways, comparable to another body humor, blood, which is also produced by the body's activities acting upon qi, and is a sticky substance that shares some of the same potential pathologies with phlegm: deficiency, inadequate circulation, firm coagulation, and complexing with heat or cold factors.
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