Caged Bird by Maya Angelou.

A free bird leaps
on the back of the wind   
and floats downstream   
till the current ends
and dips his wing
in the orange sun rays
and dares to claim the sky.

But a bird that stalks
down his narrow cage
can seldom see through
his bars of rage
his wings are clipped and   
his feet are tied
so he opens his throat to sing.

The caged bird sings   
with a fearful trill   
of things unknown   
but longed for still   
and his tune is heard   
on the distant hill   
for the caged bird   
sings of freedom.

The free bird thinks of another breeze
and the trade winds soft through the sighing trees
and the fat worms waiting on a dawn bright lawn
and he names the sky his own

But a caged bird stands on the grave of dreams   
his shadow shouts on a nightmare scream   
his wings are clipped and his feet are tied   
so he opens his throat to sing.

The caged bird sings   
with a fearful trill   
of things unknown   
but longed for still   
and his tune is heard   
on the distant hill   
for the caged bird   
sings of freedom.

Source: The Complete Collected Poems of Maya Angelou