The Phantom of the Opera by Gaston Leroux:
Such simplicity baffled him. He did not know what to say in the presence of this candid and perfect faith in a genius who came down nightly from Heaven to haunt the dressing-rooms at the Opera.
He now realized the possible state of mind of a girl brought up between a superstitious fiddler and a visionary old lady and he shuddered when he thought of the consequences of it all.
“Is Christine still a good girl?” he asked suddenly, in spite of himself.
“I swear it, as I hope to be saved!” exclaimed the old woman, who, this time, seemed to be incensed. “And, if you doubt it, sir, I don’t know what you are here for!”
Raoul tore at his gloves.