After his death on 3 June 1924, a letter was found in Franz Kafka’s office in Prague addressed to Max Brod. “Dear Max, My last request: Everything I leave behind me ... in the way of diaries, manuscripts, letters (my own and others’), sketches and so on, to be burned unread.” His friend did not honour Kafka’s wishes. “Brod was unshakably convinced of their immeasurable value to contemporary and future humanity, and he was right,” says Ross Benjamin, whose new translation of the Czech writer’s diaries is published in this centenary year of Kafka’s death. Two months after Kafka died,...