一個螃蟹 He Becomes A Crab
好大聖，捻著訣，搖身一變，還變做一個螃蟹，淬於水內，徑至牌樓之前。原來這條路是他前番襲牛魔王盜金睛獸走熟了的。直至那宮闕之下，橫爬過去，又見那老龍王與九頭蟲合家兒歡喜飲酒。行者不敢相近，爬過東廊之下，見幾個蝦精蟹精紛紛紜紜耍子。好大圣，捻着诀，摇身一变，还变做一个螃蟹，淬于水内，径至牌楼之前。原来这条路是他前番袭牛魔王盗金睛兽走熟了的。直至那宫阙之下，横爬过去，又见那老龙王与九头虫合家儿欢喜饮酒。行者不敢相近，爬过东廊之下，见几个虾精蟹精纷纷纭纭耍子。
逐句解 Line by line
That fine Great Sage! He pinched a magic sign, shook himself and changed, and became a crab once again; he dropped into the water and went straight to the front of the ceremonial arch.
捻著 takes the durative 著 zhe, a sign held between the fingers while something else is done. 還 is hái, again — and the word is doing real work, since he has been a crab before in exactly this pool. 一變 and 一個 both take 一 at yí before a falling syllable. 淬 is to quench hot metal, borrowed again for a body going under.
It turned out that this was a road he had come to know well the time before, when he raided the Bull Demon King and stole the golden-eyed beast.
了 is the perfective le and 的 is de, closing a relative clause on 路. The raid referred to is in the sixtieth chapter, where the Bull Demon King came to this same Green Wave Pool to drink and Pilgrim made off with his mount — so Pilgrim's familiarity with the road is earned in the text and not asserted here for convenience.
Going right down below the palace gate-towers, he crawled sideways across, and saw the old Dragon King and the Nine-Headed Worm drinking merrily with the whole household.
合家兒 takes 兒 at the neutral er, a true retroflex suffix. It is the second of the chapter's five, after 一門兒 in Pilgrim's ultimatum — and the two are opposites in sense, one household to be spared and one at its dinner. Both 那 are deictic and supplied by position. 橫爬 — crawling sideways — is what a crab does, and the narrator says it because the disguise is being kept up.
Pilgrim dared not go near. He crawled along under the eastern gallery and saw a number of shrimp-sprites and crab-sprites amusing themselves in a confused throng.
相 is xiāng, the reciprocal, and 不 takes bù before the dipping 敢 gǎn. 耍子 keeps 子 at the neutral zi. 紛紛紜紜 doubles two binomes for disorder, and the crab-sprites are of course the company a crab can join without being noticed.
The disguise is chosen for the water and the road is remembered from a previous raid, and the novel is careful to say both. The word 還 — again, once more — carries the first point in a single graph: he has been a crab in this pool before. The second gets a whole sentence of explanation, opening with 原來, the narrator's marker for a fact the reader needs and could not have supplied.
What he finds when he gets in is a party. The Dragon King and his son-in-law are drinking with the whole household, which is exactly what the previous passage said would happen and is also, at this moment, a failure of watchkeeping. Nobody is guarding anything.
The last thing he sees is a crowd of shrimp-sprites and crab-sprites playing about under the eastern gallery. He is a crab. The passage does not point this out, and does not need to; the next passage will have him talking to them.