I suppose it's a sort of shallow reference to keeping a child locked up in a tower away from the world. Not sure it's a great comparison since the woman raising Rapunzel disowns her when she discovers she's been sleeping with a prince, and blinds him. But they find each other by her voice, her tears heal his eyes, and he takes her back to his kingdom. So I guess the moral is if you keep your innocent child locked away from the world the only people who will make an effort to find them are gallant princes.
> So I guess the moral is if you keep your innocent child locked away from the world the only people who will make an effort to find them are gallant princes.
The moral sounds to me more like: if you keep your innocent child locked away from the world, you might just create a cure for blindness.