Happiness and Time
At its heart Slaughterhouse Five is the story of Billy's search for happiness. Ultimately he discovers that this is only possible without the baggage of the past or fear of the future. Although only the war years are presented in chronological order, Billy experiences both war and peace in essentially the same manner - as a series of events that either feel good or bad and which he deals with as best he is able at the time. Arguably, Billy's epiphany in the woods, in which he first travels through time, is the realization that as the Tralfamadorians put it he is caught in time "like a bug in amber." Thus, it is very human and natural that he should be able to experience the happiest moment of his life during a nap he takes in the back of the horse-drawn wagon while surrounded by the ruins of Dresden. As long as one accepts each moment as inevitable it is possible to simply be happy.
Billy tells the Tralfamadorian guide that it sounds like the aliens don't believe in freewill and the alien responds that of all the planets it has visited the notion of freewill exists only on Earth. This exchange highlights one of the novel's central themes, that freewill is a creation of the human mind and is meaningless in the context of the greater workings of the universe and the unalterable flow of time. The aliens advise Billy to not worry about the bad times and focus instead upon the good times which is a theory very much in keeping with the prayer displayed upon Billy's office wall and between Montana Wildhacks' breasts. The alien point of view is that if one cannot change the past, present or future then one is free to simply exist and this, the novel seems to suggest, is perhaps the most beneficial interpretation of freewill.
The opening and closing chapters of the novel detail the author's frustration in composing the work. "There is nothing to say about a massacre" observes Vonnegut and since it is always quiet after a massacre the only thing being said is what the birds say which is "Poo-tee-weet?" By introducing his "novel about Dresden" with this disclaimer Vonnegut sets up his work as not only the story of Billy Pilgrim but as a representation of everything a disaster means, details which rarely have anything to do with the disaster itself. Thus, a person like Rumfoord, who reduces the destruction of Dresden to numbers, cannot understand as well as Billy that on the ground the numbers meant very little to the survivors who simply tried to go on living. Significantly, the moment that Vonnegut intimates will be the climax of the novel, namely the senseless death of Edgar Derby, is glossed over when its time comes even though the event is discussed every time Derby's name is mentioned. In this manner Vonnegut conveys the futility of documenting a disaster by refusing to relate the disaster itself and instead telling the story of everything that happened around it.
In Slaughterhouse Five dying is not a tragic event nor is the death of anyone or anything given more importance than another person or thing. Whether it is the death of Martin Luther King, a character in the novel, the microbes in Billy's jacket or Vonnegut's own father the event is accompanied by the Tralfamadorian mantra "So it goes." The representation of death in the novel, then, is devoid of sadness or blame and embraces the inevitability of the event without regard for its cause. In fact, Billy experiences his own death many times as a time traveler and does not fear it because he knows it is simply a purple light and a soothing hum. In this way Slaughterhouse Five presents death as a detail that pales in significance to the larger experience of life.