…the volatile artifacts … some samples of our daughter Esther’s speech, recorded and written. A language archive of the girl. Paper and tapes, a broad syllabus of topics, a spectrum of moods. Our viral girl, fourteen years old, singing, laughing, yelling, whispering, arguing, speaking sotto voce, making up words. Reciting letters, numbers, crying out in pain. Even some foreign language statements, which I had instructed Esther to recite phonetically.”
-- Samuel (Narration)   (Part 1, Chapter 1)

Importance: This quote describes one of the few things Samuel and Claire take with them when they evacuate their home after the children, with their toxic use of language, have been quarantined. They are so desperate to hold on to some kind of connection with their daughter that they take the recordings even though language, in both written and spoken forms, is becoming toxic. Later in the narrative, the recordings play an important role in manipulating Samuel into working for a company...