Henry Adams’s letters are among the best in the language. They are, in Alfred Kazin’s words, “magnificent, his most spontaneous and freest literary works.” With the completion of this edition, they may well be judged his most significant achievement. “The letters are not a gloss on a life’s work; in a real sense they are his life’s work,” the reviewer for American Literature stated. We encounter Adams in 1892 at a turning point in his career, at the beginning of the period in which his leading ideas would be crystallized and his major literary works take shape. He had survived the shock of his wife’s suicide and had completed his great History of the Jefferson era, and after his long journey in the South Seas his frustrated passion for Elizabeth Cameron had begun to calm. His wanderlust now took him to the Carolinas and the Rockies, to Mexico, Cuba, Egypt, the Near East, Greece, Italy, central Europe, Russia, and the North Cape. His interest came increasingly to center on the geopolitical present and the medieval past. Prompted by the Panic of 1893, he began an intensive study of the new finance capitalism and the imperial power it created; by the end of the decade he was beginning to foresee the shift of global dominance from Britain to the United States and Russia. Meanwhile a tour of the churches and abbeys of Normandy fired his imagination and led to the absorption in the art and culture of medieval France that would bear fruit in Mont-Saint-Michel and Chartres. At his home on Lafayette Square, across from the White House, he became an informal adviser to statesmen, John Hay and Theodore Roosevelt among them. Out of his friendly association with scientists and his own study of science came his conviction that the dynamo and radium were bringing a revolution in physics. His germinating ideas about science, technology, and economic power were conveyed in his letters over many years before they were formulated into The Education of Henry Adams, his “Study of Twentieth-Century Multiplicity.”The Adams who emerges from the letters is far more complex, contradictory, and human than the protagonist of the Education. He writes to women, Mrs. Cameron above all, about politics, economics, and science as well as social news and palace gossip, just as he writes to men about art as well as power. The multiplicity of his interests, his sharp perceptions, eye for telling detail, and passion for generalization, together with his irony and wit, make his letters the engrossing record of an extraordinary life-in-progress and an incomparable commentary upon his age.