進來的路兒 I Have Forgotten the Road In
三藏道：「進來的路兒，我通忘了。」行者道：「莫說你忘了。他這洞，不比走進來走出去的，是打上頭往下鑽。三藏道：「进来的路儿，我通忘了。」行者道：「莫说你忘了。他这洞，不比走进来走出去的，是打上头往下钻。
逐句解 Line by line
Tripitaka said, "The road I came in by — I have forgotten it entirely."
A small helpless admission, and the diminutive on 路兒 makes it smaller still. 通 here means wholly or clean through, so it is not that the memory is hazy but that there is none.
Pilgrim said, "Never mind your forgetting it."
Eight characters of brisk dismissal, and the reason follows immediately: the road would have been no use to him anyway.
"This cave of hers is not the kind you walk into and walk out of. You come in by boring down from the top."
The verb is 鑽, to bore or drill — the same one Pilgrim guessed at on the hillside before he had seen the place. There is no door and no path. There is only a hole and the direction you go through it.
Tripitaka has forgotten the way in, and it turns out not to matter, which is a neatly managed piece of plotting. The novel raises a practical worry and dissolves it into a much worse one.
The mechanics of this cave are the chapter's real invention. Every other lair in the book has a gate you can knock down. This one is entered vertically, through an opening the size of a jar mouth, and the whole geometry of a rescue changes accordingly.