The first contrast concerns the differences between white and black people,indeed the
pronoun "I" refers to black people and the pronoun "They" refers to white people
The second contrast concerns the transition from today's conditions to
tomorrow's conditions.
The third contrast concerns the place where he eats today,in the kitchen,and
where he will eat tomorrow,at the table
The last contrast is that in the first part the poet
sings America while in the last part he is America
The poet is optimistic about the future and he is proud to
be black