Wisława Szymborska was once asked by an aspiring writer to provide a definition of poetry. She answered with kindly irony:

‘A definition of poetry in one sentence — please. We know at least five hundred from various sources, none of which strike us as both all-embracing and pleasingly precise. Each expresses the taste of its own age. Our native scepticism saves us from attempting new definitions. But Carl Sandburg’s lovely aphorism comes to mind: “Poetry is a diary kept by a sea creature who lives on land and wishes he could fly.” Will that do for now?’

From Szymborska’s Advice for Authors, translated by Clare Cavanagh.