It’s April 7, 1976, and Neville is exploring the Los Angeles Public Library, intent on finding some books about blood. As he walks through the library, he imagines a sad librarian, shutting down the building for the last time, probably “never knowing the fierce joy and attendant comfort of a loved one’s embrace, a tragedy” even worse than becoming a vampire. Neville finds some books on blood in the “Medicine” section of the library, and takes them back home with him.
Neville is always conscious of his own loneliness and isolation. As he walks through the library, thinking about the sad, lonely librarian, he’s really thinking about his own situation: to be the last man left on Earth is, indeed, a fate worse than death, and worse than becoming a vampire.
Neville reads that there are two ways to activate the lymphatic system: breathing and physical movements (such as compressions of the chest). But vampires do not breathe, he knows—at least not the dead vampires. This means that at least half of the dead vampires’ lymphatic flow is cut off, which would explain their pale skin and rotting odor. He also reads about how bright sunlight can kill off many bacteria. As he reads, Neville finds it hard to concentrate, and wonders why he can’t force himself to focus. He wonders, “Was it just reactionary stubbornness, or was it that the task would loom as too tremendous for him if it were germs?”
Neville continues to immerse himself in medical knowledge, hoping it will help him learn more about the vampires. One of the most interesting parts of this section is that Neville is a little reluctant to study his enemies: it’s much easier for him to believe that vampires are evil, supernatural creatures than it is for him to understand the scientific causes of their state. One could generalize this point to apply to any unknown, frightening group: it’s often easier to treat the group as a frightening “Other” than to understand the group.
Neville begins to develop some theories about the vampires. The vampire plague is certainly bacterial in nature; it’s possible that it spread so quickly because the vampires themselves wander all over town at night, spreading their bacteria. Neville also knows that mosquitos and other insects played a role in spreading the plague. Finally, Neville begins to realize that the vampire microbe forces its host to enter a coma during the daylight, so that sunlight won’t kill the bacteria. As he thinks, he feels a strong temptation to give up and get drunk; however, he forces himself to concentrate.
Vampires spread their sickness to other people in the act of sucking blood from their victims; furthermore, they enter a coma during the day because they need to protect themselves from the sunlight (vampires aren’t just sleeping during the day—that’s why Neville can move them around without waking them up). Neville has to force himself to continue working, rather than giving in to his own alcoholism.
Neville goes to sleep, still thinking of explanations for how the vampire plague spread so quickly. At three in the morning, he wakes up to the sound of a dust storm blowing outside. In a fraction of a second, “he made the connection.”
The vampire plague spreads across the city (and, perhaps, the world) because dust storms blow vampire bacteria through the atmosphere.