Trees delineate borders in Frost’s poetry. They not only mark boundaries on earth, such as that between a pasture and a forest, but also boundaries between earth and heaven. In some poems, such as “After Apple-Picking” and “Birches,” trees are the link between earth, or humanity, and the sky, or the divine. Trees function as boundary spaces, where moments of connection or revelation become possible. Humans can observe and think critically about humanity and the divine under the shade of these trees or standing nearby, inside the trees’ boundary space. Forests and edges of forests function similarly as boundary spaces, as in “Into My Own” (1915) or “Desert Places.” Finally, trees acts as boundaries or borders between different areas or types of experiences. When Frost’s speakers and subjects are near the edge of a forest, wandering in a forest, or climbing a tree, they exist in liminal spaces, halfway between the earth and the sky, which allow the speakers to engage with nature and experience moments of revelation.
In Frost’s poetry, birds represent nature, and their songs represent nature’s attitudes toward humanity. Birds provide a voice for the natural world to communicate with humans. But their songs communicate only nature’s indifference toward the human world, as in “The Need of Being Versed in Country Things” (1923) and “Never Again Would Birds’ Song Be the Same” (1942). Their beautiful melodies belie an absence of feeling for humanity and our situations. Nevertheless, as a part of nature, birds have a right to their song, even if it annoys or distresses human listeners. In “A Minor Bird” (1928), the speaker eventually realizes that all songs must continue to exist, whether those songs are found in nature, as with birds, or in culture, as with poems. Frost also uses birds and birdsong to symbolize poetry, and birds become a medium through which to comment on the efficacy of poetry as a tool of emotional expression, as in “The Oven Bird” (1920).
Solitary travelers appear frequently in Frost’s poems, and their attitudes toward their journeys and their surroundings highlight poetic and historical themes, including the figure of the wanderer and the changing social landscape of New England in the twentieth century. As in romanticism, a literary movement active in England from roughly 1750 to 1830, Frost’s poetry demonstrates great respect for the social outcast, or wanderer, who exists on the fringes of a community. Like the romanticized notion of the solitary traveler, the poet was also separated from the community, which allowed him to view social interactions, as well as the natural world, with a sense of wonder, fear, and admiration. Able to engage with his surroundings using fresh eyes, the solitary traveler simultaneously exists as a part of the landscape and as an observer of the landscape. Found in “Stopping By Woods on a Snowy Evening” (1923), “Into My Own,” “Acquainted with the Night,” and “The Road Not Taken” (1920), among other poems, the solitary traveler demonstrates the historical and regional context of Frost’s poetry. In the early twentieth century, the development of transportation and industry created the social type of the wandering “tramp,” who lived a transient lifestyle, looking for work in a rapidly developing industrial society. Like Frost’s speakers and subjects, these people lived on the outskirts of the community, largely away from the warmth and complexity of human interaction.