金蟬長老 The Elder Golden Cicada
行者道：「獃子又胡說了，你不知道。師父是我佛如來第二個徒弟，原叫做金蟬長老，只因他輕慢佛法，該有這場大難。」行者道：「呆子又胡说了，你不知道。师父是我佛如来第二个徒弟，原叫做金蝉长老，只因他轻慢佛法，该有这场大难。」
逐句解 Line by line
Pilgrim said, "The idiot is talking nonsense again. You do not understand.
獃子 takes the everyday unstressed zi, as it does throughout — register decides that ending, not whether the word names a person.
The master is the second disciple of our Buddha Tathagata, and was originally called the Elder Golden Cicada. It is only because he made light of the Buddha's Law that he must have this great ordeal."
場 is cháng here, the measure word for an event that runs its course — one whole ordeal — not the chǎng of a physical place. The cicada of the name is an emblem of rebirth: the insect sheds its shell and climbs out transformed, which is what this man is doing across a hundred chapters.
Here is the frame the whole novel hangs on, dropped almost casually into a sickroom argument. Tripitaka is not simply a monk with a fever. He is a fallen disciple of the Buddha working off a karmic debt, and every disaster on the road is scheduled.
That changes what the illness means. It is not bad luck and it is not a demon's doing — it is an instalment. Pilgrim is explaining to Bajie that you cannot buy a coffin for a man whose suffering is an accounting entry.
The name is beautifully chosen. A cicada spends years underground, surfaces, splits its shell and flies. The Elder Golden Cicada is doing the long dark middle of that process on a straw mat in a monastery, and does not know it.