In James Baldwin's music-ridden "Sonny's Blues," the narrator brother sits in the shadows of the nightclub and realizes the "awful relationship" between the musician and his instrument; a relationship much like that between the soul and the body.  For, the musician fills his instrument with the "breath of life, his own."  As he watches and listens to his brother Sonny, the narrator perceives on Sonny's face the "fire and fury" of the engagement of soul and body.  He listens to Sonny's own blues:

For, while the tale of how we suffer, and how we are delighted, and how we may triumph in never new, it always must be heard.  There isn't any other tale to tell, it's the only light we've got in all this darkness.

As the music becomes Sonny's, the narrator realizes that he, too, must share in this experience, freeing Sonny from his blues, even if only for a moment. In this sharing, meaning is given to Sonny's music.  As a toast to this accomplishment, the narrator offers drinks to the musicians.  When the waitress brings Sonny a Scotch and milk, Sonny sips from it and looks to the narrator, and nods in acknowledgement of their communion.  For the narrator who understands this communion of their souls--a bond formed by the music and its soulful evocations--the drink that is placed on the top of the piano glows as it becomes symbolic of the suffering and trouble Sonny has experienced.  But, now it is the "very cup of trembling" in which the narrator has partaken, too.