"When I Heard the Learn'd Astronomer" was written by poet, teacher, and Civil War volunteer nurse Walt Whitman. Whitman first published "When I Heard the Learn'd Astronomer" in 1865 in his poetry collection Drum-Taps. In the poem, Whitman conveys his belief in the limits of using science to understand nature. Rather, Whitman suggests, one needs to experience nature for true understanding, instead of measuring it. The poem is an example of Whitman's characteristic free verse.