] It is the moment when Catherine finally grows up. The scales fall from her eyes and she sees clearly what she has been doing to herself and others with her wild imaginings.

Isn't it interesting that Catherine did not seem to learn from her previous two experiences with unfounded imagining: the non-adventures in her own room, with the white cotton counterpane in the chest and the washing-bills in the cabinet. After each of those incidents, she is shamed and humbled -- "Heaven forbid that Henry Tilney should ever know her folly!" Yet mere hours after the washing-bills incident, she is once more letting her fancy run wild, speculating about the General's character. I guess Henry's reprimand was indeed necessary to finally dislodge Catherine's persistent fanciful notions.