開山鑿路 Opening Hills And Cutting Roads
行者笑道：「你這老兒，俱言之欠當。你初然說這山徑過有八百里，你等又不是大禹的神兵，那裡會開山鑿路？若要我師父過去，還得我們著力，你們都成不得。」行者笑道：「你这老儿，俱言之欠当。你初然说这山径过有八百里，你等又不是大禹的神兵，那里会开山凿路？若要我师父过去，还得我们着力，你们都成不得。」
逐句解 Line by line
Pilgrim laughed. "Old fellow, what you all say is not quite to the point.
當 is dàng in 欠當, fitting or apt — automatic transcription gives dāng here.
"You said at the outset that it was eight hundred li across this hill. You are not Yu the Great's divine troops — where would you get the skill to open hills and cut roads?"
那 is the open-ended nǎ — "where," meaning nowhere. Yu the Great is the flood-tamer of high antiquity who cut channels through mountains to drain the empire; invoking his divine work-gangs is a way of saying the job is beyond human hands.
"If my master is to get across, it will still take our effort. None of you can do it."
著 reads zhuó in 著力, to apply force — the third distinct reading this character takes in the chapter, alongside the marker zhe and the contact-made zháo. 得 is the full verb dé in 還得 and the light de in 成不得, where the verb stands in front of it.
Pilgrim turns the road-cutting down on grounds of scale. Eight hundred li of hill against five hundred households of farmers — and it is the same arithmetic he used earlier to shame them into hiring somebody, now pointed the other way to stop them helping.
The comparison with Yu the Great is exact rather than merely grand. Yu is the figure who did precisely this — opened hills, cut channels — and he did it with divine troops. The villagers have hoes.
What he does not say is what the effort will actually consist of. That is now twice he has told somebody he has a way of handling a thing without saying what it is, and both times the person asking has had to ask again.