名之曰將軍 The Drug Called The General
沙僧乃道：「大黃味苦，性寒無毒。其性沉而不浮，其用走而不守。奪諸鬱而無壅滯，定禍亂而致太平。名之曰『將軍』。此行藥耳，但恐久病虛弱，不可用此。」沙僧乃道：「大黄味苦，性寒无毒。其性沉而不浮，其用走而不守。夺诸郁而无壅滞，定祸乱而致太平。名之曰『将军』。此行药耳，但恐久病虚弱，不可用此。」
逐句解 Line by line
Sha the monk then said, "Rhubarb is bitter in flavour, cold in nature, and without poison.
Sha the monk answers an order with a textbook entry, and he has it word-perfect. Flavour, nature, toxicity, in that fixed order — this is the standard opening of a materia medica article, the Ming equivalent of reciting the label off the bottle.
"Its nature sinks and does not float; its action runs and does not stay.
A matched pair: it does X and not Y, it does A and not B. The balance is the form these drug descriptions always take.
"It carries off every stagnation and leaves no obstruction; it settles disorder and brings about great peace.
And here the recital walks out of medicine and into politics without warning. Carrying off stagnation is a purgative; settling disorder and bringing about great peace is a chancellor. The shift is deliberate, and it sets up the next line.
"It is named The General."
Rhubarb really is called The General in the pharmacopoeia, on account of the violence with which it works. Everything in the previous line has been walking towards that name. 將 is jiāng in 將軍.
"But this is a drug that moves things through. I fear that after so long an illness he is depleted and weak, and it should not be used on him."
And having built the drug up, he uses it to object: a general is exactly what a patient weakened by long illness cannot survive. The argument is medically sound. 行 is xíng here — a drug that makes things move through — one of the few places in this chapter where the character is not part of 行者, Pilgrim's own name.
Sha the monk answers an order with a textbook entry and he has it word-perfect — flavour, nature, toxicity, then the drug's action in matched pairs. Nothing in it is invented. Any Ming reader with a little schooling would have recognised the standard account of rhubarb.
Then the recital walks out of medicine and into statecraft. Settling disorder and bringing about great peace is the language of a chancellor, not a laxative, and it lands one line before the name that explains it: rhubarb is called The General, for the force with which it clears everything out.
Having built the drug's authority up, he uses it to object. A general is exactly what a patient weak from three years of illness cannot survive. It is a good argument, and it is the first of two the disciples will make and lose.