Upon Silence sets Long-legged Fly, a late poem of Yeats which portrays three momentous figures in history absorbed in silent contemplation: Julius Caesar planning a crucial military campaign, Helen of Troy as an adolescent in Sparta and Michelangelo painting the Sistine Chapel.

The verses are set in a syllabic manner, while each successive chorus is set to increasingly lengthy melismas as, like the long-legged fly above water, the voice hovers above the strings.