Wealth as corruption
The pearl arrives as salvation and works like poison. It makes the doctor treat a baby he'd refused, makes neighbors into thieves, makes a priest count his share, and makes Kino strike Juana and kill a man. Juana sees it first—'It is like a sin'—and she's right before anyone can prove it. Steinbeck's point isn't that money is bad but that sudden wealth in an unequal town doesn't lift a poor man; it strips him, because everyone around him believes he doesn't deserve it and acts on that belief.
Characters:KinoJuanaThe doctor