Is there a lesson,what is it

Wow, I wish I could say, "this is it in a nutshell," but with C.S. Lewis........... that's not going to happen. The Narnia Chronicles are based on Christian beliefs and themes, the lessons to be learned are moral, they're life lessons.

I'm attaching the link to a fantastic article below. If you need something else please let me know, but I think it really has everything you need to formulate your answer to this question.