Leaves of Grass is a poetry collection by the American poet Walt Whitman (1819-1892). Though the first edition was published in 1855, Whitman spent his entire life writing and re-writing Leaves of Grass, revising it in several editions until his death. This resulted in vastly different editions over four decades-the first a small book of twelve poems and the last a compilation of over 400 poems. The poems of Leaves of Grass are loosely connected and each represents Whitman's celebration of his philosophy of life and humanity. This book is notable for its discussion of delight in sensual pleasures during a time when such candid displays were considered immoral. Where much previous poetry, especially English, relied on symbolism, allegory, and meditation on the religious and spiritual, Leaves of Grass (particularly the first edition) exalted the body and the material world. Influenced by Ralph Waldo Emerson and the Transcendentalist movement, itself an offshoot of Romanticism, Whitman's poetry praises nature and the individual human's role in it. However, much like Emerson, Whitman does not diminish the role of the mind or the spirit; rather, he elevates the human form and the human mind, deeming both worthy of poetic praise. With one exception, the poems do not rhyme or follow standard rules for meter and line length. Among the poems in the collection are "Song of Myself", "I Sing the Body Electric", "Out of the Cradle Endlessly Rocking". Later editions included Whitman's elegy to the assassinated President Abraham Lincoln, "When Lilacs Last in the Dooryard Bloom'd". In popular culture Leaves of Grass plays a prominent role in the AMC TV series Breaking Bad. For example, episode 5.8 - titled "Gliding Over All" after poem 271 in the book - pulls together many of the series' references to Leaves of Grass, including the fact, noted in episode 4.4, "Bullet Points" and made more salient in "Gliding Over All", that the main character, Walter White, shares Walt Whitman's initials. Numerous reviewers have analyzed and discussed the various connections among Walt Whitman/Leaves of Grass/"Gliding Over All", the character Walter White, and the show Breaking Bad. Leaves of Grass plays a major role in the John Green novel Paper Towns. The 1989 film Dead Poets Society makes repeated references to the poem O Captain! My Captain! from Leaves of Grass, along with other references to Whitman himself.