第四鍾 The Fourth Cup
道士連忙雙手拿一個紅棗兒茶鍾奉與唐僧。他見八戒身軀大，就認做大徒弟；沙僧認做二徒弟；見行者身量小，認做三徒弟。所以第四鍾才奉與行者。道士连忙双手拿一个红枣儿茶钟奉与唐僧。他见八戒身躯大，就认做大徒弟；沙僧认做二徒弟；见行者身量小，认做三徒弟。所以第四钟才奉与行者。
逐句解 Line by line
The Daoist hurriedly took up in both hands a cup with red dates in it and presented it to the Tang Monk.
雙手 again, both hands, the correct respectful presentation — the same gesture he used for the first round of tea. Everything about the service is identical to the innocent round that preceded it, which is exactly why nobody looks twice.
Seeing that Eight Rules had the biggest frame, he took him for the senior disciple;
身軀 is bodily bulk, physical frame. He is ranking four strangers by size, which is a perfectly reasonable guess and completely wrong.
and Sha Monk for the second;
Seven characters. The narrator is going down a list, and lists in this book are usually about to have something wrong with them.
and seeing that Pilgrim was small in build, took him for the third.
身量 keeps 量 as liàng, a noun — stature, build — rather than liáng, to measure. The rule across the corpus is that the verb reading belongs in verse rhyme position and the noun reading everywhere else, and this is prose.
And so it was only the fourth cup that was handed to Pilgrim.
才 is the character carrying this sentence: only then, not until. Pilgrim is served last because he looks least important, and the whole rest of the chapter follows from that. Ten characters, and they are the hinge.
Here is the mistake, and it is made out of nothing but a glance. The Daoist ranks the disciples by size — big man first, middle man second, small man last — and serves them in that order. It is what anyone would do. It is also precisely backwards.
The reason it matters is arithmetic. There are five cups, four with red dates and one with black, and the black one is his own. Whoever is served last is the person still holding a cup when the tray is nearly empty and the odd one out is visible. By seating Pilgrim at the bottom of the order, he has given the sharpest pair of eyes in the room the longest look at the tray.
And this is the chapter's argument about its own hero, made without a word of comment. Pilgrim is small. Every demon in the book underestimates him on sight, and the underestimation is not a character flaw in them — it is a correct reading of the evidence available. He simply is a little monkey with a big frame of reference, and the book never tires of the joke.