In what ways does the novel challenge us to reconsider our notion of who is and isnt suffering from a mental illness?

The novel challenges us to look at our very "sane" systems of dealing with the mentally ill as more twisted than the people we think are sick. The main characters like the Chief and McMurphy have insight into the world that most people don't have. Indeed the Chief sees and feels things that "normal" people don't. He is not understood and deemed crazy. I think a theme here is that we are so numb in our materialistic scientific world that we have ceased to recognize the fantastic. What is hidden to us may not be hidden to people like the chief.