What is the imgaery in the poem, "As I grew older", by Langston Hughes?

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:

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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

Of
sun!

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.