有風方起浪 No Waves Without A Wind
大聖轉身道：「是你孫老爺齊天大聖也。」老魔笑道：「你是孫行者？大膽潑猴，我不惹你，你卻為何在此叫戰？」行者道：「『有風方起浪，無潮水自平。』大圣转身道：「是你孙老爷齐天大圣也。」老魔笑道：「你是孙行者？大胆泼猴，我不惹你，你却为何在此叫战？」行者道：「『有风方起浪，无潮水自平。』
逐句解 Line by line
The Great Sage turned round: "It is your Grandfather Sun, the Great Sage Equal to Heaven."
孫老爺 — Old Master Sun, Grandfather Sun — is the self-aggrandising form he uses on monsters, and it puns on his surname, which also means grandson. He is announcing himself as the elder while calling himself the junior.
The old fiend laughed: "You are Sun Wukong?"
He asks the question he already knows the answer to, which is what people do when they need a moment.
"Bold, insolent ape! I have not provoked you — so why are you here calling for a fight?"
為何 takes 為 at wèi, the for-what-purpose band, against the wéi of being or becoming that turns up twice in the reply. The complaint is also, on its face, false: this cave has been trying to eat his master since the previous chapter.
Wukong said, "'Only with a wind do waves get up; with no tide, water levels itself.'"
A two-part proverb, and Wukong is using it as an accusation: waves need a wind, so if there is trouble, somebody made it. Chinese argument leans on these paired sayings the way English leans on precedent.
The exchange is a formal challenge scene and both parties know the moves. Wukong announces his titles, the demon affects not to recognise him, and then they argue about who started it — which, in a book where the pilgrims are walking through somebody's territory to reach India, is not a trivial question.
The proverb does real work. Wukong is not saying he was provoked; he is saying that provocation is the only thing that produces this kind of disturbance, and inviting the demon to work out which of them supplied it. It is a more sophisticated opening than hammering on the door, which is how he opened this round.