小的口訣 He Lacks the Shrinking Formula
拿在手中，仔細看了又看，比前番假的果是不同。只見祥光晃晃，瑞氣紛紛，上有三十六縷紅絲，穿經度絡，表裡相聯。原來行者只討了個長的方法，不曾討他個小的口訣，左右只是那等長短。沒奈何，只得搴在肩上，找舊路而回，不題。拿在手中，仔细看了又看，比前番假的果是不同。只见祥光晃晃，瑞气纷纷，上有三十六缕红丝，穿经度络，表里相联。原来行者只讨了个长的方法，不曾讨他个小的口诀，左右只是那等长短。没奈何，只得搴在肩上，找旧路而回，不题。
逐句解 Line by line
He took it in his hand and looked at it carefully over and over: set against the counterfeit of the time before it was plainly not the same.
仔 is zǐ in 仔細, not the zǎi pypinyin supplies — the graph is never-trust and supplying its compulsory spec with the wrong value is a recorded failure of this pipeline. 看了又看 doubles the verb across the perfective.
He saw only an auspicious light dazzling and a lucky vapour thick about it, and on it six-and-thirty strands of red silk, threaded through warp and net, inner and outer answering each other.
⚠ 晃 is huǎng at both graphs — of light that dazzles, not of a thing that sways — and the shift probe alone caught it, the graph being unguarded. 度 is dù and 相 the reciprocal xiāng. The thirty-six strands set against the seventh she named give the fan a mechanism rather than a mere potency.
It turned out that the Pilgrim had asked only for the method of making it long, and had not asked her for the formula of making it small; so it stayed at that length, do what he would.
⚠ Both 長 here are cháng, the adjective and then the noun — 長的方法 stands in parallel with 小的口訣 — where the same graph was the verb zhǎng in the previous passage. 原來 marks the discovery as belated.
Having no help for it, he could only hoist it onto his shoulder, find the old road and go back; of which no more.
沒 is méi and 只得 takes dé. 不題 is the storyteller's formula for dropping a thread, and it closes the Great Sage's part in this chapter.
This is the chapter's real ending for the Great Sage, and it is a defeat disguised as a success. He has the true fan, he has the working charm, and he has asked one question too few. The Rākṣasī told him how to make it large because that is what he asked; nobody told him how to make it small again, and the novel notes the omission in a single sentence beginning 原來.
The failure is exactly of a piece with everything else he has done in these two chapters. He concealed his errand from the Jade-Faced Princess and started a brawl; he named the Iron-Fan Princess to the Bull King and lost a pardon; he got the fan from the Rākṣasī and did not think to ask the second half of the procedure. Each time the intelligence is adequate and the interrogation stops one question early.
The image the chapter leaves him with is domestic and faintly absurd: the Great Sage Equal to Heaven walking home along the old road with a four-metre fan on his shoulder, unable to fold it. 沒奈何 — having no help for it — is the same phrase used of him at the drinking table, and it is the last thing said of him before the narrative leaves to follow the Bull King.