What is love, and why are some people unable to find it? What is loneliness, and why does it hurt? What are relationships, and how and why do they work the way they do?

Answering these questions, laying bare the heart's deepest secrets, is this book's aim. Since the dawn of our species, human beings in every time and place have contended with an unruly emotional core that behaves in unpredicted and confusing ways. Science has been unable to help them. The Western world's first physician, Hippocrates, proposed in 450 B.C. that emotions emanate from the brain. He was right-but for the next twenty-five hundred years, medicine could offer nothing further about the details of emotional life. Matters of the heart were matters only for the arts-literature, song, poetry, painting, sculpture, dance. Until now.

The past decade has seen an explosion of scientific discoveries about the brain, the leading edge of a revolution that promises to change the way we think about ourselves, our relationships, our children, and our society. Science can at last turn its penetrating gaze on humanity's oldest questions. Its revelations stand poised to shatter more than a few modern assumptions about the inner workings of love.

Traditional versions of the mind hold that Passion is a troublesome remnant from humanity's savage past, and the intellectual subjugation of emotion is civilization's triumph. Logical but dubious derivations follow: emotional maturity is synonymous with emotional restraint. Schools can teach children missing emotional skills just as they impart the facts of geometry or history. To feel better, outthink your stubborn and recalcitrant heart. So says convention.

In this book, we demonstrate t...