“I still get nightmares.” 

From the very start, the novel introduces the theme of haunting and repetition. Johnny suffers from nightmares after his exposure to the manuscript—he cannot save himself from this overwhelming force. These nightmares continue to plague him throughout the novel. Further, the house itself can be viewed as a nightmare, defying real-world physics and being haunted by an entity that never fully presents itself.

“You’ll watch yourself dismantle every assurance you ever lived by.” 

These lines introduce the overarching theme of instability. The manuscript is a destabilizing object that calls into question all things that used to be stable, as does the house. Gravity, physics, and consciousness are all called into question over the course of the book. 

“Too many important things in The Navidson Record jut out past the borders.” 

These lines touch on the issue of boundaries compromised. Nothing seems to be self-contained, like the house, the text, the characters themselves, but rather bleed into each other and cause identity to be questioned. Ambiguity—a central trait of postmodern literature—is everywhere in House of Leaves.