In the poem "I Know Why the Caged Bird Sings" by Maya Angelou, Angelou contrasts the caged bird with the free bird. In doing this, she emphasizes the plight of the bird in the cage.
The caged bird is held by "bars of rage." This imprisonment goes deeper than simply putting the bird in a cage, for "his wings are clipped and his feet are tied." This bird is not only caged but also physically bound. His confinement is all invasive and takes any possibility of freedom away from him. The bird's only solace is that he can still sing out. Even though imprisoned, the bird cannot be silenced. Therefore, the "bars of rage" are the bird's pent up frustration and anger at his situation.
On the other hand, the free bird can "claim the sky" (7); he can achieve anything he desires and go wherever he pleases. However, the caged bird "stands on the grave of dreams" (27). Even though the caged bird's dreams are limited because of his confinement, he will still be heard. Both birds become a metaphor for people who are free contrasted to those who are not free. This metaphor lends itself to the themes of oppression, racism, and abuse. Therefore, it is easy to understand why the caged bird rages at the bars of injustice.