Assonance

Assonance repeats a vowel sound in neighboring words: the long "i" sounds of "the light of the fire is a sight" stretch the line's music. Where alliteration plays on consonant attacks, assonance colors the very substance of the voice — vowels carry the sentence's melody.

Each vowel has its tonality: "oo" and "o" darken, "ee" sharpens, "ah" opens. Without turning this into a mechanical correspondence chart, sound-aware writers choose words for their timbre too. Assonance was, before rhyme, the structuring principle of early epic poetry.