We're thinking Andersen was one giant history nerd, based on how much history (of Denmark and Europe in general) he includes in his stories. Famous kings and inventors pop up in his tales, and many of his characters think about the past and long for it. Some of them are haunted by old, unhappy memories, while others relive joyous memories as often as they can. But indulging in nostalgia can have a hefty price: if you live in the past too much, you'll neglect the present.
Living in the past is no substitute for living in the present.
If we can't learn from the past, we're screwed.