The primary imagery in the poem is light and dark. The speaker of the poem compares his dream to the sun. Standing between the speaker and the sun are a wall and a shadow, blocking the light of the dream. The speaker sees "Only the thick wall./ Only the shadow."
In the third stanza we learn what the shadow and thick wall represent: the speaker's dark skin: "I am black." His dream for the future is denied him because of his race.
The last stanza is a plea that his dark hands can break through the obstacles created by his dark skin:
Help me to shatter this darkness,
To smash this night,
To break this shadow
Into a thousand lights of sun,
Into a thousand whirling dreams
These last lines contain a powerful mixture of light and dark imagery. The speaker believes in the possibility of his being able to break through the social barriers of being born black in a white dominated society. He sees the possibility of reaching the light, his dream. This poem ends with hope and strength.