The author uses the characters of the doctor, the little girl, and her parents to show that emotions sometimes get in the way of what society expects from people. This is shown by the fact that the doctor who at first glance seems to be zealous and quite frank is angered and shows a peculiar, but perhaps crucial, yearning for violence. In a sense, the doctor is in some way satisfied when hurting the little girl. This is known by the fact that the doctor knows he can and should come
back in an hour or two but does not. The author leads the reader to wonder if the doctor really did the right thing. Did he do it for professional reasons or did he do it because he was overwhelmed by fury? It's left to the reader to decide which it is.
The author does a good job in setting the reader in the right direction. Williams clearly shows that the protagonist in this short story is the doctor. The doctor's job is to diagnose the little girl and the girl, not wanting to open her mouth, shows that she is the antagonist. Williams also uses the parents of the girl to show that the doctor has authority and power over the situation. The author gives the reader a clear sense that the doctor is better educated and that the family isn't all that well off. This allows the doctor to observe his surroundings, feel some urge to hurt this girl, and then use it to satisfy his own repressed and most likely unconscious desires of aggression.
In the story Williams uses the character of the doctor to demonstrate how even a professional has repressed emotions that at times surface, and in this case break free. He makes it so the reader can enter the mind of the doctor and feel what the doctor is feeling. These elements allow the reader to focus on the main idea of human imperfection. The author was trying to reveal that what makes human's human are the imperfections we all possess.