Considering he wrote The Chronicles of Narnia, one of the most popular collections of children's literature of all time, it's no real surprise that C. S. Lewis received thousands of letters from youngsters during his career. What's admirable is that he attempted to reply to each and every one of those pieces of fan mail, and not just with a generic, impersonal line or two.The fantastic letter seen below is a perfect example. It was sent by Lewis to a young American fan named Joan Lancaster in June of 1956 — just a few months before the seventh and final book of the series, The Last Battle, was published — and is actually an invaluable, generous response filled with practical writing advice, all of which still rings true.