In James Baldwin's "Sonny's Blues," music is the central focus of Sonny's life—it is the only thing that seems to release him from his suffering: his addiction, growing up black, feeling alone and cut off from others, and a feeling that he has no one to love or understand him.
Baldwin believed in the power of art to save people from suffering, or at least to minimize their suffering.
It is not surprising that Baldwin gives Sonny's character the ability to play jazz—the blues—to better deal with his own suffering, including the awareness that he and his brother cannot communicate and therefore have no connection.
Sonny tries to verbalize to his brother just how important music is to him:
"Sometimes you'll do anything to play, even cut your mother's throat." He laughed and looked at me. "Or your brother's." Then he sobered. "Or your own."
The difficulty is that Sonny wants to make his living in a non-traditional way, one that his brother does not understand. The narrator knows nothing about jazz: he believes it is simply men sitting and fooling around with music. The narrator cannot see that it is so much more to the serious musician—and to Sonny, who has music in his soul. The narrator has been charged by his mother to care for Sonny, but he doesn't know how—certainly not in a way that will help Sonny.
Ironically, the music that Sonny's brother knows nothing about ultimately creates a bridge between the two men. And while the narrator may not completely understand jazz or the blues, while he may not know anything about the big names of this movement in music, he suddenly is able to better know his brother by seeing his connection to song.
...Sonny played. Every now and again one of them seemed to say, amen. Sonny's fingers filled the air with life, his life. But that life contained so many others... Then he began to make it his...it was no longer a lament...Freedom lurked around us and I understood, at last, that he could help us to be free if we would listen, that he would never be free until we did.
Not only does the music help the narrator better know his brother, but the blues bring to him the sources of his own suffering:
I saw my mother's face again, and felt, for the first time, how the stones of the road she had walked on must have bruised her feet. I saw the moonlit road where my father's brother died. And it brought something else back to me, and carried me past it, I saw my little girl again and felt Isabel's tears again, and I felt my own tears begin to rise.
Perhaps in losing his daughter, the narrator could never quite understand Sonny's suffering because it was different than his own; but Sonny's music illuminates the truth of suffering—a common feeling for a different reason. He understand life better, and death; and most certainly, he sees what a miracle music is to Sonny, and even how much it matters in his own life.