The theme of the poem "Sympathy" is racism, and the imprisoning effect it has on the soul.
In the poem, the poet Paul Lawrence Dunbar compares himself to a caged bird. He can empathize with how the bird feels; just as the bird looks with longing at the beautiful world just beyond the bars that cage him in, so the poet, as a black man in America in the early 1900s, feels about his situation as a victim of a racism and discrimination in his society.
The poet goes beyond the empathy he feels for the caged bird in the second stanza of the poem, when he develops his theme further, describing the helpless rage both he and the bird feel as they look out from behind the bars that confine them at opportunities and freedoms others can enjoy but which they are denied. Like the bird, he "beats (his) wings" ferociously against the cage's cruel bars, but to no avail.
Finally, in the last stanza, exhausted and in pain from his futile attempts to escape his prison, the poet identifies the song of the caged bird. It is not "a carol of joy or glee", but a desperate prayer for deliverance, for the bird and for himself, that one day both "would be free".
While racism is one theme of Paul Laurence Dunbar's poem "Sympathy," in a broader sense, oppression is also a theme.
The son of slaves, Dunbar was restricted in the development of his talents by the Jim Crow Laws, which operated from 1877 into the 1960s. These laws enforced segregation, which became a literal and figurative barrier behind which African-Americans were held. Thus, the cage of Dunbar's poem becomes the symbol of the social restrictions and confinement to a low social status and few opportunities.
Yet despite this social suppression, the heart and spirit of man as the "caged bird" express themselves in song (i.e.poetry), keeping hope alive in the oppressed's heart.
And a pain still throbs in the old, old scars
And they pulse again with a keener sting--
I know why he beats his wing!
The caged bird continues to sing despite his captivity and his bruised wing and sore bosom. But it is not a joyous tune that he sings. Instead, it is a psalm that he chants, a prayer to Heaven that the suppression of his soul will end and he will be able to live without social restrictions, restrictions symbolized by the bars against which the caged bird beats his wings.