In even a short run of spontaneous, unliterary speech, some combinations of consonants and vowels are certain to recur, even though we don’t take special note of them. On the other hand, if a few vowels and consonants recur with more than average frequency, we can’t avoid noticing their sound, and we become conscious as words as an auditory experience, not merely as a medium for conveying information. For many centuries now English poetry has used this recurrence of sound expressively, organizing phonic repetition so that it becomes clearly audible and relevant to other constructive aspects of a poem…

– Alfred Corn, THE POEM’S HEARTBEAT