大驚失色 The Colour Left His Face
三藏聞言，大驚失色。一是馬的足下不平，二是坐個雕鞍不穩，撲的跌下馬來，掙挫不動，睡在草裡哼哩。行者近前攙起道：「莫怕，莫怕，有我哩。」三藏闻言，大惊失色。一是马的足下不平，二是坐个雕鞍不稳，扑的跌下马来，挣挫不动，睡在草里哼哩。行者近前搀起道：「莫怕，莫怕，有我哩。」
逐句解 Line by line
At these words Tripitaka was seized with fright and the colour went out of his face.
大驚失色 is still ordinary Chinese for going white with shock — greatly startled, colour lost. Four characters, and the novel gets an entire reaction out of them without describing anything.
First, the horse's footing was uneven; second, he was sitting none too steadily in the carved saddle — down he came off the horse with a thump, unable to struggle up, lying in the grass and groaning.
The novel offers two reasons for the fall and neither is the real one. 一是 and 二是, firstly and secondly, are the vocabulary of a careful explanation, and they are being spent on a man who fell off a horse because he was frightened. 一 keeps its full yī here, because it is being counted off against 二 rather than modifying anything. 掙挫 is to strain against something and 掙 is zhèng — the same compound is sealed four times in earlier chapters and all four agree. The 哩 at the close is the particle that does the work of a shrug.
Pilgrim came up, helped him to his feet and said, "Don't be afraid, don't be afraid. You have me."
有我哩 is three characters and it is the entire relationship. Not I will protect you, not there is nothing to fear — just you have me, and it ends on the same 哩 his master was groaning on a line earlier. Repeating 莫怕 is how you speak to somebody who has stopped listening.
This is comedy, and it is comedy of a particular kind: the narrator keeps a completely straight face. Tripitaka hears that demons have eaten the world, and the novel reports that the horse's footing was uneven.
The joke works because the explanation is so well organised. Firstly and secondly belong to a considered argument, and they are being used to file a report on a frightened man falling into some grass. Nobody says he was scared. The two careful reasons say it for them.
Then the tone changes in three characters. Pilgrim does not argue with the fear or promise that the demons are imaginary. He says you have me, which is both the least reassuring sentence available and, in this book, entirely sufficient.