Franklin Delano Roosevelt famously declared that “the greatest duty of a statesman is to educate." The central claim of Why Moralize upon It? is that it is not only statesmen who can help educate a democratic citizenry, but also novelists and filmmakers. This book’s title is drawn from Melville’s “Benito Cereno.” Near the end of this novella, after he has put down a rebellion of enslaved Africans, the American captain Amasa Delano claims...