it occurs in the great opening line: In Xanadu did Kubla Khan … Did you see it? Look again. Nothing? It’s not a symmetry of grammar, or words being mirrored; yet there is a reason why that line rolls off the tongue like the milk of paradise. Give up? An – Ah – Oo – i – Oo – Ah – An In Xanadu did Kubla Khan It’s a chiasmus of vowels. Tennyson wrote: Beneath the thunders of the upper deep Ee – e – u – e – o – e – u – e – ee A symmetry of assonance.
