A prominent, recurring theme in Sonny's Blues is the conceptual tie between light and dark and the beliefs of the narrator and his brother, Sonny. In the traditional sense, light often symbolizes truth and enlightenment while darkness suggests the abysmal and totally contradicts any notions its opposite may kindle. It can be taken that the narrator chooses the path of light because though he still resides in the same area in which he grew up, he has become an educator and escaped a fate that so many of his peers share: drug abuse and lives filled with debauchery. Sonny, though good hearted by nature, chooses a much less respectable path than his brother. He falls into heroin use that eventually lands him in jail instead of a gig with a jazz band as a great musician, something he aspires to be. The traditional meaning of the contrast between light and dark directly relates to the lives of the two brother's in Sonny's Blues because they, in many ways, reflect the brothers themselves by illustrating Sonny as the dark and the narrator as the light by highlighting and comparing the decisions the brothers made until the end of the story.
From the beginning, the narrator introduces the imagery of light and dark that will come to be the dominating theme of the story. In the first scene, the narrator is contemplating Sonny's fate in the dark subway. The "swinging lights of the subway car" allow him to read about Sonny's arrest, while the "darkness roared outside.” While seemingly just a clever use of diction for nothing more than rhetoric purposes, it soon becomes obvious that the use of the premises of light and dark in the story are the most significant in the story because the relationship between the two concepts mirror the lives of the two brothers. A grade school algebra teacher, the narrator describes many of the boys he teaches as being "filled with rage." He then says that these boys know only two "darkness’s." This illustrates that "the darkness of