The free bird leaps
on the back of the wind
and floats downstream
till the current ends
and dips his wings
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.
In the first stanza of the poem the writer talks about the life of a free bird but in the second stanza she talks about a caged bird. The technique being used in this instance is ______