The Blues of music is a genre created by African-Americans in the Deep South during the nineteenth century; the word blues refers to what was called "the blue devils" by the African-Americans, a name given to overwhelming feelings of melancholy and sadness.
In James Baldwin's story, "Sonny's Blues," the plot revolves around Sonny's misdirected attempts to silence these "blue devils" by the seductive use of heroine and, then the freedom of music. After he has been arrested for heroine use, Sonny and his estranged brother reunite as the brother brings Sonny to his home. When Sonny ventures to invite his brother to the nightclub where he performs, the brother understands how deeply Sonny has felt the vicissitudes of life as he listens in the dark to his talented brother. He also realizes that through music, Sonny is able to diffuse his suffering:
...the man who creates the music is hearing something else, is dealing with the roar rising from and void and imposing order on it as it hits the air. What is evoked in him, then, is of another order, more terrible because it has no words, and triumphant, too, for that same reason....For, while the tale of how we suffer, and how we are delighted, and how we may triumph is never new, it always must be hear. There isn't any other tale to tell, it's the only light we've got in all this darkness.
Always any form of the fine arts--which music, of course, is--feeds the soul. Thus, Sonny's suffering soul is nurtured through his piano playing. The glass of Scotch and milk atop the piano of Sonny is likened by the brother to the "very cup of trembling," the chalice, which is a symbol of suffering and, specifically, the suffering which Sonny has experienced. Like religion, the music, too, allays his "blues."
Near the end of "Sonny's Blues," James Baldwin gives a "play-by-play" account of how Sonny expresses his feelings through his piano playing.
When Sonny begins to play, he is tentative:
He and the piano stammered, started one way, got scared, stoped; started another way, panicked, marked time, started again...
When Sonny moves on to a song called "Am I Blue," he becomes "part of the family" of musicians:
He seemed to have found, right there beneath his fingers, a damn brand-new piano.
At this point, Sonny begans to use the music to tell the story of his life, both past and future:
I heard what he had gone through, and would continue to go through until he came to rest in earth.
Sonny's brother, who is listening, sees in his mind's eye his mother, his uncle, his little girl who died as a child.