Humans have long thought of their bodies and minds as separate spheres of existence, with the body as physical and the mind as mental. But such thinking is a barrier to discovery and understanding, and a new framework is needed, argues neuroscientist Joseph LeDoux. He shares his latest research, which says that human beings are a composite of four fundamental realms of existence—biological, neurobiological, cognitive, and conscious. Together our realms account for all of what and who we are, LeDoux says.