"I hold any writer sufficiently justified who is himself in love with his theme." -- Henry James
The Twelve Caesars is the only book my grandfather (a serious autodidact) ever told my parents I shouldn't be allowed to read. You see, it mentions homosexuality. My mother to her credit told him that he had taught her the evils of censorship, though she probably didn't put it just that way. The book she didn't want me to read was Catcher in the Rye, but she didn't actually forbid it.