'What is time?' St Augustine exclaimed. 'If no one asks me, I know; if I want to explain it to someone... I do not know.' Literary writers have been trying to explain it ever since: Robert Langbaum, in The Mysteries of Identity, traced in modern letters 'the Wordsworthian notion that the forgotten past comes suddenly alive in the present and establishes when it does the only continuity of self that matters'. Randall Jarrell (1914-1965) remains best-known as a critic and reviewer, or else as a poet of World War II ('The Death of the Ball Turret Gunner', 'Eighth Air Force', 'Losses'), deriving his distinction from character, voice and subject. Jarrell was also one of few twentieth-century poets to examine experienced time, not just as matters of character and psychology, but as part of the shape of a poem. Drawing on Proust, Rilke, Wordsworth and Freud - and on his own sense of how poems take place - Jarrell found distinctive forms with which to represent at once our passage from moment to moment, and our progress from childhood into old age. Jarrell's characters try to understand how their present selves have emerged from their pasts. His verbal repetitions, and his structural choices, enact those understandings: they show how those personae consider their life stories, and on how we might comprehend our own.

To see how Jarrell's poems solve problems about time, we need to begin with certain philosophical queries about personal identity. In one sense 'personal identity' ...