The speaker says they will be ashamed because they will see how beautiful he is.
This poem is in response to Whitman's "I Hear America Singing". In the poem Hughes, contrasts Whitman's idea that America is a place where everyone has value. However, Hughes does not see the same America as Whitman. People of his race are constantly tossed aside and banished to back rooms. They are not valued or respected. He tells the audience that "they" meaning the white people will be ashamed when they learn all that the African Americans have to offer the world.
