Between the mid-eighteenth century and mid-twentieth century western poetry is transformed. Poets acquire unprecedented freedom; they can write in an obscure manner, break the rules of metre and syntax, regenerate vocabulary, eliminate any mediation between their own biographical person and the character which says ‘I’ in the texts. Poetry becomes the most self-centred genre in modern literature. By analysing some exemplary texts, the author reconstructs the successive stages in this metamorphosis and interprets them as a symptom of profound historical changes.