Which Tolkien essay is famous for arguing that Beowulf is primarily poetry, not merely historical material?

Tolkien's famous essay on Beowulf is Beowulf: The Monsters and the Critics.

Tolkien delivered the lecture at the British Academy in 1936, and it was published in 1937. The essay challenged approaches that treated Beowulf mainly as a source for historical information about Germanic society. Tolkien argued that the poem's monsters were central to its artistic design rather than embarrassing distractions.

He presented Beowulf as a work carefully balanced around the human confrontation with mortality, especially through the figures of Grendel, his mother, and the dragon. The lecture helped redirect modern Beowulf scholarship toward literary analysis.

The essay became influential far beyond Old English studies. It is also important for understanding Tolkien's own imagination, because it shows how seriously he valued mythic structure, monsters, and the emotional power of heroic poetry.