In Fall on your Knees, how does music change Materia's life?

Music transforms Materia's life several times over, starting with the first time she meets James and ending with the Lebanese record she receives from her sister. When James forbids her to play the piano, Materia falls into a depression which is only alleviated when he allows her to accompany Kathleen's singing lessons. Her first paying job finds Materia playing music to accompany silent movies at the Empire Theatre, allowing her to finally mix musical genres and songs in a way that upset James but amuses the theater audience.