This is a synthetic collection covering the years 1854 to 1892 with some material still undated. Strengths of the collection include nearly 30 poems or poem fragments and Whitman's autograph revision of the "Analysis of Poems" by Dr. R. Bucke. This essay was written for Bucke's authorized biography (Walt Whitman, 1883) and Whitman's extensive revisions were incorporated before publication. The correspondence includes two longer runs, one to William O' Connor and the other to his wife Ellen O'Connor. The O'Connors were active in a number of social causes, as well as devoted advocates of Whitman and his writing. William O'Connor, author of The Good Gray Poet (1866), was one of Whitman's closest friends until an argument in 1873 caused a break in their friendship. Others who figure prominently in the Berg Collection's Whitman materials include John Burroughs (1837-1921), nature writer, literary critic, and author of Notes on Walt Whitman as Poet and Person (1867); Peter Doyle and Harry Stafford, young friends of Whitman's; and Richard Maurice Bucke (1837-1902), Whitman's authorized biographer, friend and literary executor. In addition to writing Walt Whitman (1883) and Walt Whitman, Man and Poet (1897), Bucke co-edited with Horace Traubel and Thomas Harned The Complete Writings (1902).