Fairy stories
CS Lewis dedicated The Lion, The Witch and the Wardrobe to his goddaughter. He wrote in the preface,
My dear Lucy,
I wrote this story for you, but when I began it I had not realized that girls grow quicker than books. As a result you are already too old for fairy tales, and by the time it is printed and bound you will be older still. But some day you will be old enough to start reading fairy tales again. You can then take it down from some upper shelf, dust it, and tell me what you think of it. I shall probably be too deaf to hear, and too old to understand a word you say, but I shall still be
your affectionate Godfather,
C. S. Lewis
"Some day you will be old enough to start reading fairy tales again." I love this line even though I don't think it really applies to me, since I don't think I ever stopped reading and enjoying fairy tales and children's novels. (Or, as I'd like to think, good fairy tales and children's novels, since I rate my own taste in this kind of thing.) And I'd like to think that's because I was wise beyond my years rather than that I never grew up. 😆
Of those books, there are many that I think I'll always love. Some are ones I read as a child or a teenager, like the Narnia books. If teenage books count, I'd also add The Animorphs and maybe The Harry Potter series (or at least up to and including Goblet of Fire). And some I discovered as an adult. Among those is The One and Only Ivan, which was written by K.A. Applegate, the author of The Animorphs, and shows she still has an extraordinary ability to write a beautiful, engrossing, moral tale from an animal's perspective. I also have to include The Little Prince, a charming and deep piece, at least as far as those books go.
And yet another is The Velveteen Rabbit, a very short, lesser-known work for young children. I ordered a copy for a friend's child recently and it arrived today. The copy I bought is labelled an "illustrated gift edition", but it wasn't gift wrapped, and as I picked it up I realised that I had never read a physical copy of the book. I'd only ever read it online. So I read it again.

The book tells the story of a boy who loved his toy rabbit to life. It's a charming story from start to finish: its prose, its old-fashioned feel, and the way the story develops and ends. Early in the story, the titular rabbit and an old toy horse talk about what it means to be real:
"What is REAL?" asked the Rabbit one day, when they were lying side by side near the nursery fender, before Nana came to tidy the room. "Does it mean having things that buzz inside you and a stick-out handle?"
"Real isn't how you are made," said the Skin Horse. "It's a thing that happens to you. When a child loves you for a long, long time, not just to play with, but REALLY loves you, then you become Real."
"Does it hurt?" asked the Rabbit.
"Sometimes," said the Skin Horse, for he was always truthful. "When you are Real you don't mind being hurt."
"Does it happen all at once, like being wound up," he asked, "or bit by bit?"
"It doesn't happen all at once," said the Skin Horse. "You become. It takes a long time. That's why it doesn't happen often to people who break easily, or have sharp edges, or who have to be carefully kept. Generally, by the time you are Real, most of your hair has been loved off, and your eyes drop out and you get loose in the joints and very shabby. But these things don't matter at all, because once you are Real you can't be ugly, except to people who don't understand."
This might be a bit too obvious for some adults, and I imagine it flies right over the heads of younger children. But for me it's something that adults as well as children can do with being reminded of now and then: that even though it hurts, we can, if we allow ourselves, be loved to life.
I encourage you to read it. The whole story is freely available here and likely won't take you more than 15 minutes. Or, even better, go buy a copy and read it to one of the young children in your life.