萬籟無聲 At Midnight Not A Sound
至半夜，天街人靜，萬籟無聲。八戒道：「哥哥，製何藥？趕早幹事，我瞌睡了。」行者道：「你將大黃取一兩來，碾為細末。」至半夜，天街人静，万籁无声。八戒道：「哥哥，制何药？赶早干事，我瞌睡了。」行者道：「你将大黄取一两来，碾为细末。」
逐句解 Line by line
By midnight the streets of the capital were empty of people and not one of the ten thousand sounds was stirring.
萬籟無聲 — the ten thousand sounds all silent — is a set phrase for total stillness, and it is still the phrase Chinese reaches for. The narrator gives it a clause of its own before anybody speaks.
Eight Rules said, "Elder brother, what medicine are we making?
哥哥, elder brother, takes the light second syllable that doubled family words take in Chinese — the same shape as 爺爺 or 奶奶.
"Get on with it early — I am sleepy."
幹 is gàn, to get a thing done. This is Eight Rules' entire contribution to the midnight vigil, and it is the first thing he says.
Pilgrim said, "Fetch a tael of rhubarb and grind it to a fine powder."
One order, entirely ordinary, and for the length of a single line this looks like a physician at work. 為 is wéi in 碾為, to grind into — not the wèi of doing something for a reason. 兩 is the tael, a Chinese weight of about 37 grams.
The narrator gives the silence a clause of its own, and then hands the first line to Eight Rules, who wants to know what they are making and wants to go to bed. The contrast does the work of a joke without being one.
Pilgrim's answer is a single, entirely ordinary order: a tael of rhubarb, ground fine. For the length of one line this looks like a physician at work — which is precisely the impression the next several passages will spend themselves dismantling.