"Out of the Cradle Endlessly Rocking" is a poem by Walt Whitman

Walt Whitman

Walter "Walt" Whitman was an American poet, essayist and journalist. A humanist, he was a part of the transition between transcendentalism and realism, incorporating both views in his works. Whitman is among the most influential poets in the American canon, often called the father of free verse...

, published in Whitman's Leaves of Grass

Leaves of Grass

Leaves of Grass is a poetry collection by the American poet Walt Whitman . Though the first edition was published in 1855, Whitman spent his entire life writing Leaves of Grass, revising it in several editions until his death...

 collection. "Out of the Cradle Endlessly Rocking" is found in the title section, Sea-Drift

Sea-Drift

Sea-Drift is the title of a section of Walt Whitman's great poetic work Leaves of Grass, first published in 1855. It is a compilation of poems referring to the sea or the sea-shore....

. It was originally called 'A child's Reminiscence' and was published individually by the New York Saturday Press on 24th December 1859. It was included in the 1860 edition of Leaves of Grass under the title A Word Out of the Sea (and occasionally erroneously referred to, even by Whitman himself, as A Voice Out of the Sea.)

The plot is about a young boy walking on the beach, who finds two mockingbirds

Northern Mockingbird

The Northern Mockingbird, Mimus polyglottos, is the only mockingbird commonly found in North America. This species was first described by Linnaeus in his Systema naturae in 1758 as Turdus polyglottos....

nesting and watches them. The female bird fails to appear one day, and the male bird cries out for her. The bird's cries create an awakening in the boy, who translates what the male is saying in the rest of the poem. As this happens, the boy recognizes the impact of nature on the human soul and his own burgeoning consciousness.

The poem is an excellent example of Whitman's romanticism and his recurring themes of love, sexuality, death, and loss.