The novelist Henry James said that Ralph Waldo Emerson—who was once the country’s beloved essayist-laureate, author of the iconic American effusion called “Self-Reliance” and the semiofficial philosopher of entrepreneurial individualism—suffered from a fatal flaw. Emerson’s disabling defect, James thought, was innocence: He had no “sense of the dark, the foul, the base.” The novelist said of the essayist: “A ripe unconsciousness of evil is . . . one of the most beautiful signs by which we know him.”

James and Emerson were giants of American literature long ago, but they belonged to different generations. Emerson (1803–82) wrote his important essays (those sun-shot prose miracles of the country’s morning energy) in the years before the Civil War, before that catastrophic crack in American history. James (1843–1916) composed his elaborately shadowed novels well after Appomattox. It was the Civil War that introduced the naive country to its fallen self. The conflict ushered in, among other things, Reconstruction and Jim Crow, the Gilded Age and the robber barons, mass immigration from Ireland, Italy and Eastern Europe. James and Emerson came of age in two different Americas. No wonder, then, that they had different ideas about the country’s capacity for good or evil.