The narrator, a stand-in for Vonnegut, describes a movie producer's advice about writing an anti-war book using a simile:
“You know what I say to people when I hear they’re writing anti-war books?” [...]
“I say, ‘Why don’t you write an anti-glacier book instead?’ ”
What he meant, of course, was that there would always be wars, that they were as easy to stop as glaciers. I believe that, too. And even if wars didn’t keep coming like glaciers, there would still be plain old death.
The simile compares wars to glaciers, suggesting that both are natural phenomena that are impossible to stop. This quotation is one of many self-referential moments throughout the story, where the characters in the book discuss the book itself. These meta-references contribute to the novel's experimental structure and narration. The perspective on war advanced in the simile echoes the Tralfamadorian's perspective: because wars have always and will always happen, one should simply ignore them and focus on something happier.
Despite what the glacier-war simile suggests, however, wars are a product of people, not nature. Indeed, Slaughterhouse-Five explores the human element of war through detailed descriptions of soldiers from both sides of World War II. Nevertheless, the simile is an early instance of the novel's resigned tone, suggesting the terrible horrors of war are natural and inevitable.
Vonnegut makes use of imagery and simile to describe Billy Pilgrim's experience behind enemy lines:
Billy had never seen Weary’s face. He had tried to imagine it one time, had imagined a toad in a fishbowl. [...] They had heard the dog. They had heard men calling back and forth, too—calling like hunters who had a pretty good idea of where their quarry was.
Vonnegut describes in detail what is (not) seen and what is heard, specifically the German soldiers' hunting the Americans. Slaughterhouse-Five is ladened with imagery, especially imagery of World War II and its aftermath. Any number of passages could have been used to discuss imagery in the story, but dogs come up a few times, specifically in the sections detailing the war.
Part of what makes Slaughterhouse-Five so moving is its ability to place the reader in the shoes of Billy Pilgrim and the other soldiers, and Vonnegut's imagery helps make that possible. Comparing the men to hunters is barely a simile because that is very literally what they are doing: hunting the Americans. The sounds, sights, and smells of war dominate the sections of the novel about war, and this passage is no different. The novel's ability to succeed as an anti-war novel is predicated on its ability to make the reader feel the horrors of war, and figurative language like imagery helps Vonnegut do as much.
Even the dog described above becomes a part of Vonnegut's anti-war thesis outside of the instance of imagery: later the dog is revealed to be a pet owned by a local resident and borrowed by the soldiers. Thus, even the seemingly fearsome dog helping the Nazis root out Americans is merely a pawn. Nobody wins in wartime, dogs or people alike.
Right before Billy Pilgrim becomes unstuck in time for the first time, Vonnegut compares him to a poet with a simile:
He was like a poet in the Parthenon.
The Parthenon is a temple to the Greek goddess Athena and is one of the most famous ruins from antiquity. Athena was the goddess of wisdom, warfare, and craftsmanship. The simile compares Billy Pilgrim, about to time travel in the middle of Germany and World War II, to a poet about to recite Greek poetry in a temple to the goddess of wisdom and war. The fact that Athena is the goddess of warfare begins to justify the simile, transforming Pilgrim into a poet preaching to the goddess of warfare as he faces death behind enemy lines. At the same time, comparing Pilgrim to a poet before he becomes unstuck in time for the first time somewhat undercuts his allegedly truthful account of time travel. Throughout Slaughterhouse-Five, the tools of fiction are used to reveal truths about the world. The simile, by evoking poetry before the science fiction elements of the novel come to life, once again highlights this element of the story.
Furthermore, equating Billy Pilgrim to a poet about to recite poetry in one of the most famous Greek temples suggests that what comes next will be of tremendous importance. The simile emphasizes Pilgrim's ensuing words, urging the reader to pay attention to what follows: Pilgrim becoming unstuck in time. Thus the simile elevates the importance of time travel in the novel by comparing Pilgrim to a poet preaching to a congregation in a temple of historical importance.
The narrator makes use of both a simile and an allusion to the fictional city of Oz when describing what Dresden looked like when seeing it for the first time:
The boxcar doors were opened, and the doorways framed the loveliest city that most of the Americans had ever seen. The skyline was intricate and voluptuous and enchanted and absurd. It looked like a Sunday school picture of Heaven to Billy Pilgrim. Somebody behind him in the boxcar said, “Oz.” That was I. That was me. The only other city I’d ever seen was Indianapolis, Indiana.
The city can barely be described through Billy Pilgrim's eyes: with every word he uses he has to use yet another to attempt to capture the wonder of the city, making Dresden "intricate and voluptuous and enchanted and absurd." The simile comparing Dresden to heaven suggests the city is akin to the kingdom of God, amongst the highest praise one could give. This conveys the sheer awe felt by the Americans who are viewing Dresden for the first time. The reader, however, knows Dresden will soon be burned down, and tens of thousands will be killed in the process. If Dresden is akin to heaven, the bombing of Dresden is an act of sin. Once more, the novel's anti-war sentiment is made apparent through figurative language.
The allusion to the fictional city of Oz (from the well-known book and film The Wizard of Oz) further conveys the wonder of Dresden, especially because Vonnegut inserts himself into the narrative to do so. Not only is Dresden akin to the magical city of Oz and Heaven, but it is so awe-inspiring that the narrator himself must enter the story to support the claim. Considering that Dresden is about to be destroyed, both the simile and the allusion only work to underscore the tragedy that is its impending destruction. By highlighting the wonder of Dresden through figurative language, Vonnegut ultimately indicts the collateral damage of war.
The guards standing watch over the Americans sheltering in the slaughterhouse during the bombing of Dresden are compared to a barbershop quartet with a simile:
The guards drew together instinctively, rolled their eyes. They experimented with one expression and then another, said nothing, though their mouths were often open. They looked like a silent film of a barbershop quartet.
The optometrist barbershop quartet is mentioned frequently throughout Slaughterhouse-Five, and often triggers memories of wartime. The above simile, comparing the guards to a barbershop quartet which was not singing, explains why that might have been the case. The simile works to humanize the guards, who are almost entertaining to Billy Pilgrim in this moment when, for the rest of Dresden, the world is burning. The juxtaposition between the people sheltering in the slaughterhouse, and the people burning alive in the rest of the city, makes the simile somewhat absurd: how could Pilgrim think of a barbershop quartet in this moment? A major throughline of the text, however, is that suffering is an inevitable part of life during which one should think of happier moments. This perspective on life, articulated by the Tralfamadorians, is being enacted by Billy Pilgrim as he thinks of a barbershop quartet while looking at his Nazi captors.
It is worth noting that this moment is also one of verbal irony, as the prisoners and guards are some of the only people to survive the Dresden bombing despite sheltering in a slaughterhouse. This irony contributes to the jocular tone of the scene, which clashes with the seriousness of the bombing. Overall, the verbal irony and the barbershop quartet simile alike both evidence Pilgrim's unique perspective on how to cope with the horror of war, one inspired by the Tralfamadorians.