In the months following the first edition of "Leaves of Grass", critical responses began focusing more on the potentially offensive sexual themes. Though the second edition was already printed and bound, the publisher almost did not release it. In the end, the edition went to retail, with 20 additional poems, in August 1856. "Leaves of Grass" was revised and re-released in 1860, again in 1867, and several more times throughout the remainder of Whitman's life. Several well-known writers admired the work enough to visit Whitman, including Amos Bronson Alcott and Henry David Thoreau.