Leaves of Grass is a poetry collection by American poet Walt Whitman. Though it was first published in 1855, Whitman spent most of his professional life writing, rewriting, and expanding Leaves of Grass until his death in 1892. Six or nine individual editions of Leaves of Grass were produced, depending on how they are distinguished. This resulted in vastly different editions over four decades. The first edition was a small book of twelve poems, and the last was a compilation of over 400. The collection of loosely connected poems represents the celebration of his philosophy of life and humanity and praises nature and the individual human's role in it. Rather than focusing on religious or spiritual matters, Leaves of Grass focuses primarily on the body and the material world. Its poems do not rhyme or follow standard rules for meter and line length. Leaves of Grass is regarded by many scholars as a completely do-it-yourself project. Whitman chose his idealized self as the subject of the book, created the style in which it was written and worked hard and intelligently to perfect the style over a period of six or seven years, creating the personality of the proletarian bard, the supposed writer of the poems.