[Mr. Bloom is Sterling Professor of Humanities at Yale. This essay is adapted from his introduction to "Leaves of Grass (July, 1855 ed.)," just published by Penguin Classics.]

If you are American, then Walt Whitman is your imaginative father and mother, even if, like myself, you have never composed a line of verse.

You can nominate a fair number of literary works as candidates for the secular Scripture of the United States. They might include Melville's "Moby-Dick," Twain's "Adventures of Huckleberry Finn," and Emerson's two series of "Essays" and "The Conduct of Life." None of those, not even Emerson's, are as central as the first edition of "Leaves of Grass," whose 150th anniversary we now mark.

Whitman, the American bard, our Homer and our Milton, broke the new road for the New World. D.H. Lawrence, alternately furious at Whitman and in thrall to him, saw his precursor as the poet of the Evening Land, sharing in Melville's litany for the doom of "the white race." The 20th century's dominant American writer, Faulkner, carried on from Melville in what now can be read as a tetralogy: "As I lay Dying," "The Sound and the Fury," "Light in August," and "Absalom, Absalom!" Whitman's true heirs at home included T.S. Eliot's "The Waste Land," Hart Crane's "The Bridge," and Wallace Stevens's "The Auroras of Autumn." Abroad, the catalog is too large for quick compilation: Lawrence, Lorca, Pessoa, Vallejo, Neruda, Borges, Paz are perhaps the most notable.

Walt Whitman was the crucial celebrant of what I think we yet will call the American Religion, the momentary fusion of all denominations in an amalgam of Enthusiasm and Gnosticism that marked the beginning of the end of European Protestantism in America, and which began in the Cane Ridge Revival of 1800. The Southern Baptists, Pentecostalists, Mormons, Adventists, and other native strains are ongoing emanations of what began there. Our theologians and prophets of the American Religion include Emerson, Joseph Smith, and Horace Bushnell, among others. The philosopher William James is its psychologist, and Walt Whitman forever will be its poet-prophet, who sings only songs of myself. We now have an American Jesus and an American Holy Spirit, and have largely banished Yahweh, except that he marches as Warrior God, endlessly trampling out the vintage where the grapes of wrath are stored.

Whitman's full aesthetic achievement is still undervalued and misunderstood. He is the greatest artist his nation has brought forth. Indeed, no comparable figure in the arts has emerged in the last 400 years in the Americas: North, Central, South, or the Caribbean. His six major poems: "Song of Myself," "The Sleepers," "Crossing Brooklyn Ferry," and the triad of elegies: "Out of the Cradle Endlessly Rocking," "As I Ebb'd with the Ocean of Life," and "When Lilacs Last in the Dooryard Bloom'd" have their peer only in Milton's "Paradise Lost," in Bach's endless fecundity, in the glory of Michelangelo's Sistine ceiling -- baroque masters of sublimity. To call Whitman, at his strongest, baroque must seem at first paradoxical for a poet who professes to chant "Spontaneous Me," but Whitman is no improviser. His artistry reflects conscious study of his precursors in the language, despite his American nationalist ambivalence toward British tradition....

Though Whitman later denied it, Emerson made the first "Leaves of Grass" possible. Emerson credited Whitman with the "Appalachian enlargement" of our literature. "As sane as the sun" was one of Whitman's final tributes to Emerson. My own favorite among Whitman's anecdotes is of his last visit to the then senile Emerson. The greatest of our poets so stationed his chair that he could stare fully at the benign countenance of his mentor, and each sat silently, Whitman in loving reverie, Emerson in the tragic solitude of an Alzheimer's victim. It was the final act in a grand drama of influence that is still ongoing in our literary culture.