…one of the greatest truths in psychology is that the mind is divided into parts that sometimes conflict. To be human is to feel pulled in different directions, and to marvel—sometimes in horror—at your inability to control your own actions. The Roman poet Ovid lived at a time when people thought diseases were caused by imbalances of bile, but he knew enough psychology to have one of his characters lament: “I am dragged along by a strange new force. Desire and reason are pulling in different directions. I see the right way and approve it, but follow the wrong».