Hatred
Much of the story takes place during the time of the rise of the Nazi Party to fascist power in German. The narrator presents a metaphorical portrait of the defining characteristic of fascist ideology with metaphorical language. "Hatred was like some otherworldly beast, seeded in small acts of violence and oppression against our Jewish citizens, growing in strength as the power-hungry fed it with rhetoric and propaganda." The lesson to be gained from history is that the Nazi regime did not begin with concentration camps and genocide. Fascism begins with lower-level acts of malevolence that, as this simile proposes, slowly grow into monstrous evil.
Autism Spectrum
Part of the story is set in the present day. A narrator reflects upon modern medical advancements with metaphorical exasperation. "I am a puppet controlled by medical professionals and therapists." Her son has been diagnosed as being somewhere on the spectrum of autism. Like many other maladies which have existed forever but have only recently been given names, autism is not clearly defined. This puts parents at the mercy of an ever-shifting understanding of conditions. This situation has the narrator in this instance comparing the uncertainty to being at the mercy of a greater power manipulating stimulus and response.
Nemesis
The very same mother comparing herself to a puppet also uses metaphorical language to identify a symptomatic condition associated with her son's autism as her own personal nemesis. "Echolalia is the bane of my existence sometimes." Echolalia is the medical term used when one person repeats—without intent or meaning—a word or phrase immediately spoken by another person. The bane of one's existence is itself a metaphor for anything that one considers to figuratively be the cause of all the misery in their life. Thus, her autistic son's uncontrollable habit of repeating something anyone else says has become so omnipresent that it has surpassed mere annoyance.
Randomness
One of the book's narrators observes that "Life has a way of reminding you that you are at the mercy of chance and that even well-thought-out plans can turn to chaos in an instant." Considering that half the book's narrative is situated within the horrors of Nazi oppression, one might well assume this moment of philosophic contemplation is spouted by a survivor of that unprecedented social upheaval responsible for such widespread chaos. Once again, however, the narrator here is the mother of the boy with autism, and it is his diagnosis that stimulates this metaphorical personification of chance and mercy.
Secrets and Lies
The entire narrative that unifies both narrative threads—one taking place in the past and one taking place in the present—is dependent upon those things that cannot be said. "Truths unspoken are falling out all over the place today, and it turns out there is a straw that’s just too heavy for this old camel to carry." The narrator is overcome by the anxiety produced by the management of those secrets and lies. The idiomatic metaphor of the straw that broke the camel's back is a reference to having too many secrets to keep and one too many lies to keep track of to ensure those secrets don't unravel.
