The quote from Kelley Armstrong's book "Omens" emphasizes the remarkable resilience and defensive capabilities of the human mind. It compares the mental fortifications we possess to the physical defenses that ancient Romans could have used to protect their cities. Just as fortified walls shield cities from external threats, our minds are equipped to withstand various challenges, from shocking truths to intellectual arguments. This metaphor illustrates how our mental architecture can help us cope with significant disruptions and maintain stability.

Armstrong suggests that the brain functions as a sophisticated piece of machinery that instinctively strengthens itself in the face of danger or crisis. When confronted with serious threats or ideological challenges, our mental defenses activate, allowing us to confront and process these daunting revelations. This resilience enables us to function despite the chaos surrounding us, highlighting the brain's incredible ability to adapt and protect our sense of self in a turbulent world.