During his lifetime, Franz Kafka burned an estimated 90 percent of his work. After his death at age 41, in 1924, a letter was discovered in his desk in Prague, addressed to his friend Max Brod. “Dearest Max,” it began. “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.”