An excellent book! The first section describes Tolkien's work on the Oxford English Dictionary project. Probably half of the book is devoted to uncovering the background behind Tolkien's made-up words from LOTR and other books. Besides his fictional languages, Tolkien coined many other words that have come to be used in English, as well as resurrecting old words from Old and Middle English. Tolkien's thorough knowledge of old Germanic languages and philology gave him the background he needed to create his own words convincingly. If you like reading etymologies or are a huge Tolkien fan, this is a must read.