The poem "Harlem" suggests that denying people access to their dreams can lead to explosive outcomes.
The poem was written by Langston Hughes, who was a Black man, in 1951, well before the Civil Rights Movement really gained momentum. By placing this poem in a historically Black city, Hughes was intentionally drawing attention to the dreams of Black people which had been ignored by American society. Hughes asserts that attempting to "defer" the dreams of a people does not simply extinguish the desire for those dreams.
He then asks a series of questions regarding what might happen if society continues to ignore the dreams of its Black members. Does the dream just change form, much like a dried up grape becomes a raisin? Does it turn into a festering sore, its infection spreading throughout its environment? Does it rot, its smell of decay sickening society? Perhaps it weighs people down, becoming a "heavy load" that people are forced to drag around with them everywhere they go.
The poem ends with a final question, in italics and visually distinct from the rest of the stanza. This final question implies that eventually, the deferral of dreams creates an explosion that becomes impossible to ignore. Hughes indicates that eventually, society will be forced to acknowledge the damage it inflicts upon those whose dreams are ignored.
Therefore, the ultimate statement about the human condition is that people feel compelled to continue to attempt to make their dreams a reality. When they face opposition to those dreams, they will eventually become an explosive force, demanding attention.