The most important letter in American literary history shows the leader of Boston's literary establishment recognizing Whitman's brilliant innovation and new voice. In his essay “The Poet,” Ralph Waldo Emerson had called for a voice to celebrate the poem of America itself, “Our log-rolling, our stumps and their politics, our fisheries, our Negroes, and Indians, our boasts, and our repudiations, the wrath of rogues, and the pusillanimity of honest men, the Northern trade, the Southern planting, the Western clearing, Oregon and Texas.” Whitman began writing poetry that seemed to record everything Emerson called for, and his preface to the 1855 Leaves paraphrases Emerson: “The United States themselves are essentially the greatest poem.” He sent a copy of his unsigned but registered book to Emerson and received in return the letter that launched his career as America's premier poet.