Symbol for possibility
After Mary’s mother turned into a zombie, Mary climbed the highest building in her village and looked at her surroundings. Mary describes the village she lives in and she also describes various paths that go into the woods. Unfortunately, since no one ever leaves the village, no one knows where the paths lead to. For Mary however, the paths are proof that there is life outside their closed community and they also represent for her the possibility that she could one day escape her village.
Talking about the ocean
A common motif in the novel is that Mary frequently talks about the ocean. When she takes care of Travis for example, she makes a habit out of telling him the stories her mother used to tell her about the ocean and about the beauty of it.
Everything needs to be sacrificed for the greater good
One of the motifs that appears in the novel is the idea that humans have to sacrifice their own happiness for the greater good. One of the people who believes in this idea is Sister Tabitha who tries to convince Mary to give up her obsession with Travis and to focus instead on holly things. According to her, Mary should willingly give up her own happiness just to ensure that the rest of the society goes well.
The past as a time of great pain and how God changed it all
Another motif found in the novel is the idea that nothing good happened in the past. According to Sister Tabitha, in the past, humans used to be violent, attacking one another and being controlled by grief. They did not care that their species would be wiped out and the only thing they cared about was their own well-being. This however changed when humanity rediscovered religion and God and according to Sister Tabitha, everything changed when man let God rule his life instead of trying to play God and make their own rules.
Instability
Another common motif is the idea that Cass is extremely unstable and that her mood can change extremely rapidly. Cass shifts from one mood to another really quickly and she reacts violently when something bad happens. Her behavior remains consistent throughout the novel.
