Language is the ability to communicate. Helen can communicate her feelings, but only in an undisciplined manner, such as throwing a fit. What Helen doesn't have is the ability to express the meaning of language, and this is why Annie wants to teach her hand symbols. Annie tells Kate, Helen's mother, that "Language is to the mind more than light is to the eye." The need for humans to be able to express their thoughts and feelings throught communication is essential. This is one reason why the last scene is so powerful--Helen finally learns the connection between language and meaning when she realizes what water is.