Tom Shippey investigates the linguistic, historical, and mythological foundations that allowed J.R.R. Tolkien to construct a coherent and immersive secondary world. As a scholar of Old and Middle English and a colleague of Tolkien, Shippey utilizes his academic expertise to analyze the philological roots of Middle-earth. He argues that Tolkien’s work is not merely escapist fantasy but a rigorous, scholarly attempt to reconstruct a lost Northern European mythology through the lens of modern literature.

This work is widely regarded as a foundational text in Tolkien studies due to its rigorous philological approach and the author's unique proximity to the subject matter. The text provides a dense, scholarly examination that remains accessible to readers interested in the mechanics of literary creation and the evolution of fantasy as a genre.