Explain: You do preach worse than a parson.

The daughter says that one ought not to chase away a human being whom one had invited to come and to whom one had promised Christmas cheer. To this the ironmaster says that she preached worse than a parson. It is a back-handed compliment to her powers of persuasion which tugged at his humanitarian instincts to give shelter and board to the peddler. A parson's sermons can still be ignored but this girl's suggestions could not be.