Susan Cain's new book, "Bittersweet: How Sorrow and Longing Make Us Whole." searches for the answers to why we feel melancholic.
"Bittersweet is the hidden source of our moonshots, masterpieces, and love stories," says Susan Cain. She connects the source of deepest states of affection, happiness, awe, and creativity to life as being imperfect. At the heart of her exploration is the naming and reinterpretation of the paradox that gives her her title: that there is no bitter without sweet.
"Bittersweet," which is part memoir and part scientific point of view, psychology, spirituality, religion, epigenetics, music, poetry, and art, is a plea for the underappreciated "strangely pervasive joy in the beauty of the world" in a culture of relentless optimism. The book attempts to explain the irrepressible lump in our throat that arises when we see a picture of our high school graduation as a grinning toddler.
The sadness that springs from compassion is a pro-social emotion, a means of connection and love," she writes. And this "happiness of melancholy" has a physiological impact and justification.
As Ms. Cain discovers, it unraveled that the vagus nerve - the constellation of nerves that connects the brainstem to the neck and abdomen and is responsible for digestion, breathing, and heart rate - is also connected with compassion in the face of sadness, our instinct to be and feel young and the desire to experience joy.
Fittingly, the oldest, most instinctual part of our nervous system, which evolved to give us the empathy we need to respond to our underdeveloped newborns, Ms. Cain said, is also the site of the continuum of sadness, joy, and survival that makes us human.