“Knock, knock, knockin' on heaven's door”
— Bob Dylan, Knockin' on Heaven's Door (1973)
Context
Bob Dylan wrote "Knockin' on Heaven's Door" for the soundtrack of Sam Peckinpah's 1973 Western Pat Garrett and Billy the Kid, where it scores the death of a wounded frontier sheriff who staggers to a riverbank to die as his wife looks on — the "Mama" the verses address. Released as a single in 1973, it became one of Dylan's most-performed and most-covered songs, later recorded by Eric Clapton, Guns N' Roses, and dozens of others. Dylan was awarded the Nobel Prize in Literature in 2016 "for having created new poetic expressions within the great American song tradition."
How the repetition works
The catalogue's onomatopoeic repetitions — Poe's pealing bells, Kipling's trudging boots — imitate continuous ambient sound; Dylan's doubled "knock" names a discrete human act instead, a plea for admittance at a threshold, repeated because the door has not yet opened. It is also the catalogue's first entry drawn from recorded popular song: where Burns's "red, red rose" reached back to folk lyric meant to be sung, Dylan's chorus is epizeuxis engineered as the hook of a twentieth-century studio recording, a line a crowd completes by reflex. His 2016 Nobel Prize in Literature is the formal recognition that such a lyric belongs in a catalogue of literary device at all — the doubled word working, as everywhere else here, to make a single utterance land twice.