灵枢经·病本 The Root of Disease
先病而后逆者，治其本；先逆而后病者，治其本；先寒而后生病者，治其本；先病而后生寒者，治其本；先热而后生病者，治其本。
先泄而后生他病者，治其本，必且调之，乃治其他病。先病而后中满者，治其标；先病后泄者，治其本；先中满而后烦心者，治其本。
有客气，有同气。大小便不利治其标，大小便利，治其本。
病发而有馀，本而标之，先治其本，后治其标；病发而不足，标而本之，先治其标，后治其本，谨详察间甚，以意调之，间者并行，甚为独行；先小大便不利而后生他病者，治其本也。
When illness comes first and reversal follows, treat the root; when reversal comes first and illness follows, treat the root; when cold comes first and illness follows, treat the root; when illness comes first and cold follows, treat the root; when heat comes first and illness follows, treat the root.
When diarrhea comes first and other illness follows, treat the root — one must first regulate this, and only then treat the other illness. When illness comes first and fullness in the middle follows, treat the branch. When illness comes first and diarrhea follows, treat the root. When fullness in the middle comes first and vexation of the heart follows, treat the root.
There is guest qi (an intruding pathogen), and there is qi of the same kind (arising from the body's own disorder). When urination and defecation are unfavorable, treat the branch; when urination and defecation are favorable, treat the root.
When disease arises and is one of excess, proceed from root to branch — treat the root first, then the branch. When disease arises and is one of deficiency, proceed from branch to root — treat the branch first, then the root. One must carefully and thoroughly observe whether the condition is mild or severe, and regulate it with judgment: in mild cases, root and branch may be treated together; in severe cases, treat one alone. When urination and defecation are first unfavorable and other illness follows afterward, treat the root.