What is the meaning of "bars of rage" mentioned in the second stanza?

s poem
reflects the anguish of a divided society, as she compares the free bird, who can do anything he
pleases, with the caged bird, who can only dream of happiness as he sits in his
prison.

The free bird leaps / on the back of the wind as he travels in
infinite space. He has the freedom to go anywhere and to do anything. His possibilities are
endless, so he names the sky his own. He thinks of traveling with the breeze and of the fat
worms of opportunity he has only to pluck from the grass. Staying under the warmth of the sun,
he will always have chances to achieve his dreams.

In contrast, the caged
bird sits in his cage, knowing the free bird flies and that he cannot follow. He stalks / down
his narrow cage because he is angry at his helplessness. He has no opportunity to see beyond
his bars of rage. Angelou attributes the anger to the bars of the cage, but it is really that
of the caged bird. His rage follows because he feels trapped and sees no way out of his
situation. His wings are clipped, so he can only sing about the freedom he so desperately
desires. He knows he should be out there flying in freedom instead of standing on the grave of
dreams. He has given up his goals and dreams, and only his shadow shouts now.

Angelou depicts the situation that Black Americans face in society; however, her poem
can also reflect all types of oppression. By juxtaposing the free and caged birds, she clearly
depicts the unfairness and cruelty of oppression. She pleads with her audience to understand and
to correct the wrongs.