Ever wonder why you like sad songs and rainy days? Or why you react intensely to music, art, and nature? As the author of Quiet: The Power of Introverts in a World That Can't Stop Talking suggests, those of us with this "bittersweet" state of mind must acknowledge our personal pain—whether from a death or breakup, addiction or illness—or else we may inflict it on others via abuse, domination, or neglect. But if we realize that all humans know loss and suffering, Susan Cain points out, we can turn toward one another.