With today’s poem, we commemorate the Halloween birthday of John Keats (1795–1821), the youngest and shortest-lived of the English Romantics. “La Belle Dame Sans Merci” recreates a medieval folk form, the ballad, whose quatrain we recognize by its alternation of tetrameter lines with trimeter, and its rhymes in the second and fourth lines. This was an ideal form for verse storytelling: a formal pattern of meter and rhyme that made its words both compelling to hear and easy to memorize, with enough freedom that the narrative could move the story forward.

Here we have a creepy story of the sort that medieval audiences loved — but so, nearly a century later, would William Butler Yeats. Yeats’s “The Stolen Child,” which appeared as Poem of the Day in June 2022, might have been spoken by this “Belle Dame Sans Merci,” a beautiful fairy enchanter enticing a human away from his own world and people to a shadowland of immortal captives, miserable in their unending half-life. In Keats’s poem, so appropriate to the gray waning of the autumn, the “knight-at-arms,” “loitering” alone in a barren landscape relates the tale of his enchantment to some interlocutor who — for some reason we don’t know — is also passing through this dreary region.

Besides the mesmerizing ballad form, what makes this poem so compelling are the things we don’t know. Who is this interlocutor who stops to question the knight? What is that person doing all alone by that birdless lake? And the knight himself: has he escaped from his charmed doom? Does he stand sentry, to warn other knights away? Or has the enchantress chained him there, fair as he is, to lure others in even as he cries the alarm, to entrap them forever in a wintry place where “no birds sing?” It’s that ghost-story uncertainty, full of eerie possibility, that gives this ballad its chilly post-Halloween shiver.