The primary theme of Robert Frost's "Mending Wall," first published in 1914, is the arbitrary separations that humans create between themselves. In the poem, the persona, or the poem's speaker, meets with his neighbor to rebuild a stone wall that divides their two properties. He wonders why the wall is needed in the first place. His property consists of apples trees, while his neighbor's consists of pine trees: "He is all pine and I am apple-orchard. / My apple trees will never get across / And eat the cones under his pines" (23-25). When the persona tells his neighbor this, the neighbor stubbornly repeats the adage he learned from his father: "Good fences make good neighbors" (44). The neighbor is unwilling to critically evaluate why the wall must be built. He continues to simply repair it year after year.
Frost suggests that this wall, a metaphor for the separation we establish between ourselves and those around us, is unnatural and in fact damaging to our health. The poem begins, "Something there is that doesn't love a wall, / That sends the frozen-ground-swell under it, / And spills the upper boulders in the sun" (1-3). This "something" that doesn't love the wall must be nature, for the wall is slowly eroded by natural processes. Furthermore, while placing the fallen stones back on top of the wall, the persona says, "We have to use a spell to make them balance: / 'Stay where you are until our backs are turned!' / We wear our fingers rough with handling them" (18-20). The neighbors must use "spells," a markedly unnatural process, to preserve the wall. Also, the neighbors' hands are damaged while repairing the wall, which once more suggests that this repairing is an unnatural and unhealthy activity. With this, Frost uses the mending wall as an analogy for the interpersonal barriers that we create against other individuals on the basis of tradition, despite the fact that such barriers are unnecessary, unnatural, and antithetical to our well-being.
For more information, please explore the eNotes guide for this enlightening poem linked below!