William Empson’s poem ‘Letter I’ (1928–35) appears to anticipate the black hole, using the idea of a dying star from which no light escapes as a metaphor for unrequited passion. Closer inspection of the Cambridge undergraduate context in which the poem was written, along with the other source materials incorporated besides Arthur Eddington in the poem, reveals the motivation behind Empson’s playful engagement with the limits of what was possible under general relativity. Empson’s attempt to follow the metaphysical example of John Donne, using the new cosmology of the 1920s, led him to explore an extreme astro-physical condition that Eddington had dismissed as absurd, and that still had an uncertain scientific status in the 1930s.