In 1855 Whitman published at his own expense a volume of 12 poems, Leaves of Grass, which he had begun working on probably as early as 1847. It was criticized because of Whitmans exaltation of the body and sexual love and also because of its innovation in verse formthat is, the use of free verse in long rhythmical lines with a natural, organic structure. See also the companion volume: Prose Works.