In Slaughterhouse-Five, Vonnegut takes an omniscient point of view, electing to be both inside and above the action of the text. Such a position allows him to go beyond the limits of the characters' perceptions in order to let us know what is happening both on Earth and on Tralfamadore at any given time. Vonnegut's telling us things that the characters cannot know gives us a broader perspective of time and space in the novel.
In addition to being the narrator, Vonnegut is present within the text as the narrative's central character in the first and last chapters. He appears in the text on three occasions to remind us that, although he is now above the novel's actions and is reflecting on the past events, he was once part of the action.
Along with Vonnegut's being an omniscient narrator, he demands that we participate in the narrative, He connects events that are not chronologically linear, but that exist harmoniously in psychological time. We must learn to infer transitions and to make equations between these images: In so doing, we relive — like the Tralfamadorians and Billy Pilgrim — past moments with the added knowledge of the future of those moments.
A first-time reader of Slaughterhouse-Five is likely to pass over Vonnegut's short bursts of imagery without any particular notice. Many of these images, recalled when something similar happens at a later time or in another place, connect and reconnect the novel's themes. For example, the appearance of Vonnegut's first dog not only recalls his second dog, it invokes the events of the time when the second dog appears. In turn, both dogs recall not just the presence of the German shepherd dog in Luxembourg, but the events that take place at that time. And likewise, the image of the golden cavalry boots worn by the old German corporal not only foreshadows the image of Billy's silver boots, but also events from both perspectives in time. These images are important because they help link together different scenes that occur at different times. Although individual events in Slaughterhouse-Five seem fragmented at first, Vonnegut's imagery makes the novel a cohesive whole.