I had not realised before starting work on this book how much attention had in¯uenced my thinking about mental illness and mental health. In the 1980s, I had been greatly intrigued by Pierre Janet's descriptions of attentional debility as a pathognomonic sign of hysteria. According to Janet, the (usually female) hysterical patient differed from others in an inability to talk and tap her ®ngers on command at the same time.