行不由徑 One Does Not Go By Bypaths
土地道：「大聖休焦惱，天蓬莫懈怠。但說轉路，就是入了傍門，不成個修行之類。古語云：『行不由徑。』豈可轉走？你那師父在正路上坐著，眼巴巴只望你們成功哩。」行者發狠道：「正是，正是。獃子莫要胡談，土地說得有理。土地道：「大圣休焦恼，天蓬莫懈怠。但说转路，就是入了傍门，不成个修行之类。古语云：『行不由径。』岂可转走？你那师父在正路上坐着，眼巴巴只望你们成功哩。」行者发狠道：「正是，正是。呆子莫要胡谈，土地说得有理。
逐句解 Line by line
The local god said: "Great Sage, do not fret; Marshal of the Heavenly Reeds, do not slacken.
休 and 莫 are two ways of saying "do not", used in parallel, one to each disciple, and the local god addresses each by the title that fits him. He has been the only figure in three passages to give either of them an instruction.
"The moment you speak of turning aside you have entered a side gate, and that is no kind of religious practice.
And here is the pun that is not a pun. 傍門 bàng mén is a side door — the standard term for a false spiritual path, set against the 正路, the straight road, that the master is literally sitting on. A road round the mountain is a side route in both senses at once, and the local god declines to distinguish them.
"The old saying goes: one does not walk by bypaths.
The quotation is from the Analects, said of Tàn Tái Miè Míng, who would take no short cut and never came to the magistrate's house except on public business. A Chinese reader hears the whole anecdote in four characters. The local god is quoting Confucius at a pair of Buddhist pilgrims in order to stop them walking round a mountain, and nobody remarks on the incongruity.
"How then can you turn aside?
Four characters, and they carry the whole weight of the refusal: if turning aside is already a false path, the question answers itself.
"That master of yours is sitting on the straight road, watching with all his eyes for you to succeed."
眼巴巴 is to look fixedly and helplessly, with a suggestion of waiting that cannot act. 正路 answers the 傍門 of three lines earlier and completes the figure: there is a straight road with a man sitting on it, and every other road is a side door. 著 is the zhe that keeps the sitting going, and 哩 holds at li.
Pilgrim said fiercely: "True, true.
發狠 is to steel oneself rather than to lose one's temper.
"Idiot, no wild talk. The local god speaks with reason.
The Great Sage sides with the local god against his own brother, and it takes five characters. 說得有理 takes the light linking de, hooking the verb to its result, and it is the second such site in these two passages. 獃子 takes the light 子, zi.
The local god refuses the detour on doctrinal grounds, and the whole argument turns on a pun that is not a pun. 傍門, a side door, is the standard term for a heterodox spiritual path; a road round the mountain is literally a side route; and the local god declines to distinguish the two. To speak of turning aside is already to have turned aside.
Then he quotes the Analects at them. 行不由徑 — one does not go by bypaths — is said of a man who would take no short cut and never approached his magistrate except on public business, and it is Confucian rather than Buddhist doctrine being used to keep two Buddhist pilgrims on a road. The novel makes nothing of the incongruity, which is itself characteristic of how freely it moves between the three teachings.
The closing image does the persuading. 你那師父在正路上坐著，眼巴巴只望你們成功 — a man sitting on the straight road, watching helplessly for them to succeed. It is not an argument at all, and it works: the Great Sage sides with the local god against his own brother in the space of a single line.