I have spent a great many pages in this section describing what look like separate afflictions of the human mind: our habit of confirming what we already believe, our hunger for tidy stories, our blindness to the improbable, our amnesia for the dead who leave no trace, and our tendency to fixate on a short, well-lit list of dangers while a much larger darkness waits outside it. They are not five diseases. They are one disease, observed from five rooms.