Literary terms can relate to the very title of Hansberry's drama. The title is taken from Langston Hughes's poem entitled "Harlem." The poem begins with the fundamental question of "What happens to a dream deferred?" From that point, Hughes uses figurative language to illustrate what he sees as the consequence of blighted hopes. A simile that Hughes uses to illustrate the painful condition of denied aspiration is the question, "Does it dry up like a raisin in the sun?" Hughes's employment of the simile causes reflection in the reader, while it pointedly criticizes a social order that perpetuates the withering of dreams like grapes that are exposed to the brutality of the sun. In showing the struggles of the Younger family, Hansberry dramatizes the simile that Hughes employs.
The idea of dreams being maintained and preserved despite the intensity and magnitude of the world's rejection is a critical aspect of the drama. The Younger family struggles to dream in a world that does not immediately validate such a reality. The American Dream and the costs it exacts in order to achieve it become a critical theme in the drama. At different points, this theme is illuminated through dialogue. One example is when Walter is speaking with his son, Travis, about the dreams he has and the dreams he wishes to transfer to the next generation:
And I’ll go inside and Ruth will come downstairs and meet me at the door and we’ll kiss each other and she’ll take my arm and we’ll go up to your room to see you sitting on the floor with the catalogues of all the great schools in America around you. . . . All the great schools in the world! And—and I’ll say, all right son—it’s your seventeenth birthday, what is it you’ve decided?
The ability to dream defines Walter. He exists in a world that continually puts him down, causing his dreams to dry up "like a raisin in the sun." In this, a significant theme in the drama is evident. The ability to dream is a vital theme in the drama. As Walter puts Travis to sleep and expresses to him how important dreams are to the family, to preserve them despite the intensity of forces that seek to dry them "like a raisin in the sun," the theme of dreams becomes evident.