大聖到此 What Brings You Here
行者不知此意是何，要見玉帝。天王不敢攔阻，讓他進去。徑至通明殿外，又見四大天師迎道：「大聖到此何幹？」行者不知此意是何，要见玉帝。天王不敢拦阻，让他进去。径至通明殿外，又见四大天师迎道：「大圣到此何干？」
逐句解 Line by line
Pilgrim could not make out what any of this meant, and wanted to see the Jade Emperor.
不知此意是何 — did not know what this meaning was. The narrator says it plainly rather than letting Pilgrim bluster, which is a small kindness to a character who has spent the chapter so far being certain about everything.
The Heavenly King did not dare stop him, and let him through.
不敢攔阻, did not dare obstruct. There is a long memory in that phrase: the last time Pilgrim came through this gate uninvited, the entire celestial army was unable to hold him.
He went straight to the outside of the Hall of Perfect Light, where the Four Great Preceptors met him. "What brings the Great Sage here?"
通明殿, the Hall of Perfect Light, is the antechamber to the Jade Emperor's throne room — one waits there rather than walking in. The 四大天師, Four Great Celestial Preceptors, are historical Daoist masters given heavenly office, and they are about to be named one by one.
Three sentences, three small notes of character. Pilgrim does not understand; the Heavenly King does not dare stop him; the Preceptors meet him at the door and ask his business.
The middle one carries the history. Pilgrim is walking through a gate he once broke, past guards who once fought him and lost, and the novel records their calculation in five characters: they did not dare. Nobody is hostile. Everyone remembers.