I first read The Chronicles of Narnia forty years ago, in 1977. I was twenty-one years old and working on my Bachelor's degree, and was into the whole epic/fantasy scene, having read (a couple times), The Lord of the Rings and The Once and Future King in late high school. So, I became just as fascinated with The Chronicles. What has struck me this time around is the fact that they really were written as children's book, which I didn't notice forty years ago. In other words, they seem much more juvenile to me now. But no matter—they are still great books, and among my top favorites, beloved by adults as well as children. And it is nice to take a break from the heavy stuff I often read.
Narnia was first conceived by Lewis in 1939, when three girls, Margaret, Mary and Katherine, came to live with him at the Kilns, Risinghurst because of air raid attacks by Germany in London and other cities. Aslan came into the picture because Lewis dreamed frequently about lions. Then, he says, it all came together. Still, Book One, The Lion, the Witch and the Wardrobe wasn't completed until 1949, and it took him until 1954 to complete the set. They were published between 1950 and 1956, and were not written in the order they were published, or in the order they appear now. Wikipedia has a great deal of information about the background of these stories, the characters, and lots of additional links, plus information on the movies. Only the first three books have been made into movies, and in all honesty, they weren't that great, especially compared to Harry Potter or The Lord of the Rings. Apparently, Book Four, The Silver Chair is now in production as of April 2017.
Though Narnia has become wildly popular, and will most likely remain that way, not all critics have good things to say about either the books or Lewis himself. There is the Christian thing, of course. Most people "get it" that Aslan, the Lion-savior, is Jesus, although Lewis claimed it wasn't planned that way. Others have gender/sexuality issues. And Philip Pullman (author of the best-selling trilogy His Dark Materials) wrote a rather nasty review of both the books and author called the The Darkside of Narnia. My opinion is that its just a cool fantasy series for kids. Analyze it if you want, but mostly read it and enjoy it. Forty years ago I analyzed it. This time around, I just read it for fun. But I do have to admit, there is the metaphysical aspect, and a spiritual one, too (not all Christian) that still speaks to me a deeper and inspired truth about our present reality, as I believe most of these types of fantasy stories do. This includes, for instance, ancient doorways to other realities (that many of us are working to open), and the consciousness of animals and plants, as well as the nature of reality itself.
And this one should be read by all. For an adult, none of them should take too long to breeze through. Meanwhile, if you are one of the few people who has not read any or all of these books, catch a glimpse of them here, and be inspired. The images are all taken from the first three movies.