Chaucer’s life, from birth as a vintner’s son in the 1340s to burial in Westminster Abbey in 1400, is visible not from literary genius but from his roles as civil servant and diplomat in a period of expanding bureaucracy.His intellectual range and ambitions were unusual for a layman, not only in Latin texts but also astronomy and French and Italian literature, amid other ‘literacies’ suitable for a tangential member of the courtly world.His associations, marriage, and release from a charge of rape can only be dimly and partly discerned.Clearer but still mysterious is his commitment to writing literature only in English, at a time when that lacked nationally identifying authority.Amid the several languages mingled around him in poetry and life, Chaucer’s literary monolinguism may not be simply social positioning but an aesthetic constraint, forcing innovation under formal limits as he did in other ways in poetry.