Poverty
The theme of poverty permeates all three stanzas of the poem. At every moment we are reminded of the state of the couple's possessions: chipped, worn, and creaking. The title of the poem refers to their frugal diet of beans, which often symbolize scarcity and subsistence. The space they inhabit is small and cordoned off; not only is it a single room, it is a back room, a room which, in the context of a larger structure, is marginalized by its position in the back.
Reminiscence
The poem emphasizes how the couple lives in the past. They deal with the monotony of their current lives—in which they eat the same beans every day, put on the same clothes, and clean the same tiny space—by remembering more exciting days from their past. Brooks hints to the reader that the couple may have had some exciting experiences by describing them as "Mostly Good," which leaves room for some minor misbehavior. In other words, we know that according to the speaker they haven't done anything egregious in their pasts, but they were once young people who perhaps rebelled in their own way.
Aging
The theme of aging closely relates to the theme of reminiscence because it is the fact of the couple's aging that necessitates their reminiscing. At the time of this poem's publication, a great deal of attention was being paid to youth culture. A tide of youthful rebellion and protest characterizes the sixties, and the elderly were susceptible to being cast aside in its wake. As quiet witnesses to the age, the couple in the poem live out their routine and long for the days when they were young and active, when the day was theirs.
