Susan Cain’s ‘Bittersweet’ Explores the Upper Side of Sorrow

Have you ever wondered why we love sad songs or drown in the “Thank You Mom” Olympics commercial? Questions like these have been the impetus for Susan Cain’s new book, Bittersweet: How Sorrow and Longing Unite Us. Believing that we experience the deepest states of love, happiness, fear and creativity, writes Ms. Cain, “Bitter sweetness …