Slaughterhouse

"He's not a human being anymore. Doctors are for human beings." (190). I think that Billy hasn't really been alive for a while now. He is characterized as being so imaginative, that he can be considered crazy. He no longer knows what is true and what is not. He's been this way since the war. It was only worse after the plane crash. But what really defines a human being? Is it one that is alive and understanding? Or through his craziness, can he really still be a human?