What foil is used in the play the miracle worker?

In "The Miracle Worker," the primary foil is Helen Keller's teacher, Annie Sullivan, who contrasts with Helen's inability to communicate. While Helen is trapped in a world of silence and darkness, Annie's determination and innovative teaching methods highlight the potential for growth and understanding. Their relationship emphasizes themes of resilience, education, and the struggle for self-expression, showcasing how their differences propel the narrative forward.