I think no other fictional world matches the depth of Tolkien’s. This children’s tale (The Hobbit) seized the Oxford mythologist and ancient languages scholar Tolkien and hurled him and us into a saga so vast that he never did encompass it all. The three-volumed Lord of the Rings is the central masterpiece—the journey of the hobbits, men and elves, and wizard Gandalf to destroy the Ring of Power of the dark Lord Sauron. It is a tale of surprising invention, subtlety, and insight.
— Stewart Brand
It’s worth remembering that Tolkien told these tales orally to his children before writing them down.