行者眼乖 Pilgrim Has A Sharp Eye
行者眼乖，接了茶鍾，早已見盤子裡那茶鍾是兩個黑棗兒。他道：「先生，我與你穿換一杯。」行者眼乖，接了茶钟，早已见盘子里那茶钟是两个黑枣儿。他道：「先生，我与你穿换一杯。」
逐句解 Line by line
Pilgrim's eye was sharp. He took his cup, and had already seen that the one left on the tray had two black dates in it.
眼乖 is quick-eyed, sharp-sighted — 乖 here in its older sense of clever and alert, not the modern one of a well-behaved child. And 早已, already, does the timing: he had seen it before he finished taking his own cup. Four passages of preparation and it comes apart in twenty-three characters.
"Sir," he said, "let me swap cups with you."
先生 here is simply "sir" for a Daoist, not the modern "mister". 穿換 is to exchange one thing for another, and the request is made with no explanation at all. He does not say why. He is watching what the answer will be.
Everything the Daoist built collapses on a detail he introduced himself. He needed a cup to drink from, so he made one up with black dates. Now there is a tray with one cup that does not match, and the person served last has been looking at it.
What Pilgrim does with the information is the interesting part. He does not accuse, warn his master, or knock the tray over. He asks, pleasantly, to swap. It is the move of someone who has not yet decided what he knows and wants to see the other man's face — and it puts the Daoist in the position of having to explain a thing he had hoped nobody would notice.
眼乖 is worth keeping. It is the book's shorthand for Pilgrim's one genuinely superhuman ordinary quality: not the seventy-two transformations, not the cudgel, but that he looks at things. Every trap in this novel is sprung by somebody not looking, and every trap is spotted by him looking.