斬關奪門 A General Breaching The Gate
八戒道：「巴豆味辛，性熱有毒。削堅積，蕩肺腑之沉寒；通閉塞，利水穀之道路。乃斬關奪門之將，不可輕用。」行者道：「賢弟，你也不知。此藥破結宣腸，能理心膨水脹。快製來，我還有佐使之味輔之也。」八戒道：「巴豆味辛，性热有毒。削坚积，荡肺腑之沉寒；通闭塞，利水谷之道路。乃斩关夺门之将，不可轻用。」行者道：「贤弟，你也不知。此药破结宣肠，能理心膨水胀。快制来，我还有佐使之味辅之也。」
逐句解 Line by line
Eight Rules said, "Croton seed is acrid in flavour, hot in nature, and poisonous.
Eight Rules answers in the identical form Sha the monk used — flavour, nature, toxicity — and the repetition is the joke. Neither of these two is supposed to know anything, and both can recite the pharmacopoeia on demand.
"It pares away hardened accumulations and sweeps the deep cold from the lungs and bowels; it opens what is stopped and clears the road for water and grain.
削 stays xuē, to pare away. 塞 is sè here: 康熙 files the very pairing 閉塞 under that reading, glossed 塡也，隔也 — blocked up, cut off — and records no sāi at all.
"It is a general who breaks through barriers and forces gates, and must not be used lightly."
If rhubarb is The General, croton is a general who breaks down gates. Eight Rules has answered Sha the monk's military figure with a sharper one, and the warning follows from the metaphor rather than from the pharmacology. 將 is jiàng here, the commander — not the jiāng of 將軍 a moment ago, where the same character named the drug.
Pilgrim said, "Worthy brother, you too do not understand.
The same words as the first rebuttal, with one word added. He is not arguing; he is repeating himself at whichever brother has spoken.
"This drug breaks up what is bound and opens the bowel, and can set right a swollen heart and a body distended with water.
And again the objection is not met — the drug's virtues are simply recited back.
"Prepare it quickly. I have assistant and envoy drugs to support it."
佐使 are two of the four ranks a classical prescription is built from: sovereign, minister, assistant and envoy, exactly like a court. Pilgrim answers a military metaphor with a courtly one, and promises ingredients he carefully does not name. 還 is hái, in addition.
Eight Rules answers in exactly the form Sha the monk used — flavour, nature, toxicity, then the action in matched pairs — and the repetition is the joke. Neither of these two is supposed to know anything, and both can recite the pharmacopoeia on demand.
He also sharpens the metaphor. If rhubarb is The General, croton is a general who breaks down barriers and forces gates open, and the warning that follows comes out of the figure rather than out of the medicine. The objections have escalated in step with the drugs.
Pilgrim's second reply opens in the same words as his first, with one word added. He is not arguing; he is repeating himself at whoever has spoken. The one new thing he offers is a promise of assistant and envoy drugs — the junior ranks of a proper prescription — which he conspicuously does not name.