There are two central themes in The Miracle Worker: that the human spirit can triumph over even the most daunting of disabilities and that a dedicated teacher can transform the lives of those with whom he or she comes into contact. These inspirational themes have long been personified in the widely known true-life relationship between Helen Keller and Annie Sullivan, but The Miracle Worker also dramatizes collateral issues that extend beyond the particular case. Underlying Helen’s process of learning basic principles of what Annie terms “obedience” (decorum, etiquette, and hygiene), there are more universal lessons of self-governance—the inculcation of self-restraint instead of willfulness, the development of self-discipline instead of self-indulgence. Only when these lessons have been mastered can Helen begin to acquire language—which, Annie says, “is to the mind more than light is to the eye.”

The play’s recurrent images of keys and locks are related to the learning process, which metaphorically opens the world to Helen’s innately active and inquisitive mind. Significantly, Helen’s first activity when alone with Annie is to unlock the teacher’s suitcase, finding there an unsuspected treasure, the gift of the doll. Nevertheless, possession of keys—and of the treasure that they can disclose—is not easily come by and often becomes an object of contention, like the doll itself. Those not in possession of the keys must be rescued, as when Helen, contending for mastery over her world and dominance in their relationship, locks Annie in the room (a scene establishing them as worthy adversaries and equal antagonists). There is also the risk that the key—like Helen’s newly acquired discipline—will be lost or willfully discarded, a figurative drop into darkness signified by the well. Darkness is also typically associated with blindness and ignorance, while the keys are associated with knowledge and light. Language—whether written, spoken, or signed—is the key to the soul, as the play’s epigraph makes clear:“At another time she asked, ‘What is a soul?’ ‘No one knows,’ I replied; ‘but we know it is not the body, and it is that part of us which thinks and loves and hopes.’ . . . [and] is invisible. . . . ‘But if I write what my soul thinks,’ she said, ‘then it will be visible, and the words will be its body.’”-—Annie Sullivan, 1891

Although Helen’s transformation provides the play’s central “miracle,” other characters’ lives are also changed by Annie’s presence: Helen’s older brother James gains adult autonomy standing up to his domineering father for the first time when he defends Annie’s teaching methods, and the Kellers become better parents through the example that her loving discipline for Helen provides. Annie, too, is transformed through her experience with the Kellers, gaining maturity, confidence, and authority as the play proceeds. She also escapes the guilt associated with the death of her younger brother many years before, periodically evoked by ghostly voices that are finally dispelled.