We tend to think of Freud as a great innovator, but the truth is that he himself rested, like a ship on an iceberg, on a huge body of theory and knowledge which had accumulated before his time. Even the famous Unconscious had made its appearance at least seven decades earlier. As for such supposedly modern phenomena as multiple personalities, the vogue for them began in the first half of the nineteenth century; and the first case in which the perpetrator of a murder pleaded amnesia, and got off, was in the eighteen eighties.