Of This and Other Worlds, by C. S. Lewis
Last week Scribacchina wrote about non-fiction about fairy tales, which prompted me to go through my mom's bookshelves to see what she had. I snagged four or five books, because I really need more books on my pile, and of course the one I read right away was a book of essays on stories by C. S. Lewis. I am pretty sure that will surprise no one.
It's just a collection of various pieces on one theme; some of them were never published or even finished. A couple are only a page or so long and were written for book blurbs or similar. I had fun reading them.