Cultural messages inform the populace that if they aren't perpetually electric they are missing out on the pinnacle of relatedness. Every pop-cultura… - Thomas Lewis

People rely on intelligence to solve problems, and they are naturally baffled when comprehension proves impotent to effect emotional change. To the neocortical brain, rich in the power of abstractions, understanding makes all the difference, but it doesn’t count for much in the neural systems that evolved before understanding existed. Ideas bounce like so many peas off the sturdy incomprehension of the limbic and reptilian brains. The dogged implicitness of emotional knowledge, its relentless unreasoning force, prevents logic from granting salvation just as it precludes self-help books from helping. The sheer volume and variety of self-help paraphernalia testify at once to the vastness of the appetite they address and their inability to satisfy it.

On the other side of the aisle are evolutionary psychologists and cross-cultural sociologists, who point out that the American habit of sleeping separately is a global and historical singularity. Almost all the world’s parents sleep with their children, and until the last sliver of human history, separate sleep was surpassingly rare. The burden of proof thus falls upon our culture to justify its anomalous nighttime practices.

From birth to death, love is not just the focus of human experience but also the life force of the mind, determining our moods, stabilizing our bodily rhythms, and changing the structure of our brains. The body’s physiology ensures that relationships determine and fix our identities. Love makes us who we are, and who we can become. In these pages, we explain how and why this is so.