Beowulf: The Monsters and the Critics give it a powerful effect. He rebuts suggestions that the poem is an epic or exciting narrative, likening it instead to a strong masonry structure built of blocks that fit together. He points out that the poem's theme is a serious one, mortality, and that the poem is in two parts: the first on Beowulf as a young man, defeating Grendel and his mother; the second on Beowulf in old age, going to his death fighting the dragon. The work has been praised by critics including the poet and "Beowulf" translator Seamus Heaney. Michael D. C. Drout called it the
Beowulf: The Monsters and the Critics work's wide influence. Tom Shippey wrote that the essay "was seized upon eagerly, even gratefully, by generations of critics". Alvin A. Lee wrote that "Tolkien's manifesto and interpretation have had more influence on readers than any other single study, even though it has been challenged on just about every one of its major points." Seth Lerer wrote that the essay "may well be the originary piece of modern "Beowulf" criticism. … The strategies … control the fundamental assumptions of Old English scholarship for the next fifty years." R.D. Fulk commented that "No one denies the historical importance of this lecture.