J.R.R. Tolkien is best known as the author of The Lord of the Rings. He was also Merton Professor of English language and literature at Oxford University, and a respected philologist whose passion for words and languages fueled his building of the gigantic mythopoeic history of Middle Earth. The purpose of this paper is to illustrate how his passion not only laid the foundations for this history but also contributed to the construction of the “inner consistency of reality” which the author regarded as an essential characteristic of “fairy tales”.