One of the defining features of Whitman’s work is his fascination with – and deep love for – the natural world. While “When I Heard the Learn’d Astronomer” gestures towards the divide between the scientific approach to nature and the more emotional, individualized approach of the poem’s speaker (and almost certainly of Whitman himself), Whitman’s passion for the natural world more generally is one of the recurring themes throughout Leaves of Grass. In his poetry, Whitman celebrates nature for its beauty and its many mysteries, while also drawing connections between the free spirit he believed himself to possess and the wild, untamed landscapes that allowed him to be himself. In other poems such as “On the Beach At Night Alone” and “The First Dandelion” (See Further Reading and Resources), Whitman’s characteristic preoccupation with the natural world is evident. With this in mind, it is not difficult to understand why the thematic movement in “When I Heard the Learn’d Astronomer” is towards a more direct experience of nature and away from the scientific inquiries of the astronomer. Whitman himself, like the poem’s speaker, preferred to experience nature in his own way, without the demystifying tendencies of a more academic approach.