Slaughterhouse-Two

The most repeated statement in the entire book is "so it goes." Vonnegut repeats it anytime death is mentioned. His themes are conveyed by his made up, highly stereotypical aliens, the Tralfamdorians. They have a different grasp of time than Billy Pilgrim and the rest of the inhabitants of Earth do. They see time as a human would see "the Rocky Mountains. It's all one big line." This is basically the idea that time cannot be changed, it is as set-in-stone as a mountain range is. To the Tralfamadorians, time is one big line, made up of various moments. Each moment has neither a cause nor an effect, but simply is. The question, "Why?" doesn't exist. I thought that was one of the most interesting parts of everything that's happening in this book. I think this sort of indifference and meaninglessness is Vonnegut's biggest theme too.