What is the theme in The Song of the Lark by Willa Cather?

Success, or more specifically the characteristics that define success, is another theme presented in "The Song of the Lark." While Thea becomes successful according to the standards of the world, she still wonders if she is the artist she should be. Thea's idea of success is not built upon how much money she makes or how well she is liked by her audience but by her own standards of perfection. Had Thea seen the expression on Spanish Johnny's face after he heard her perform, she would have realized how great of a success she had become.