Oedipa leaves the bar and heads toward the city. She wanders around aimlessly all night long, and she begins to confuse reality and imagination. She sees numerous ambiguous symbols all around her that may or may not relate to Tristero. In what may be a fragment of a dream, she wanders into Golden Gate Park and finds a circle of children who stay awake all night in their dreams and feel very tired when they awake the next morning. They tell Oedipa that they know about the muted post horns, and then they play hopscotch on the Tristero symbols drawn on the sidewalk in chalk. They hopscotch to a rhyme that incorporates the word Tristero as well as the phrase "Turning taxis," which Oedipa tells them ought to be "Thurn and Taxis."
In an all-night diner, Oedipa meets Jesus Arrabel, an old friend of Pierce's whom Oedipa had known briefly in Mexico. She reflects on the fact that Pierce is the reason she is linked to Arrabel, meaning that Pierce is a type of Maxwell Demon figure because he is a central figure for two different forces. On a bus in the city, she sees written the acronym D.E.A.T.H., which stands for "Don't Ever Antagonize the Horn." She sees the muted horn symbol at a Laundromat and then in a bathroom at the airport, where she also hears a mother tell her departing son to write to her via W.A.S.T.E. Oedipa's hallucinations become worse as she begins to see the muted post horns all around her. Just before dawn, she goes downtown to the Embarcadero, where she randomly meets an old man in a rooming house. The man gives her a letter and asks her to deliver it to the "horn" people, who are located under the freeway (he gives her directions). The old man claims that he is too sick and weak to deliver the letter himself. Oedipa, worrying for the old man's health, helps him upstairs to his room, where an even older man apparently lives. She gives the older man money for liquor and tells him that the younger old man will probably die from what Oedipa calls "DTs" or "delirium tremens," which constitute "a trembling unfolding of the mind's plowshare," or, in other words, a general tendency toward insanity.
Oedipa leaves the building and goes to the freeway with the old man's letter. She finds a garbage can with a "swinging trapezoidal top" on which are printed the letters W.A.S.T.E. (with periods between letters). Oedipa hides nearby and later watches a young boy deposit letters in the can. She then drops off her letter but hides some more until a man comes and picks up all the letters. She follows him around town, staying behind him after he has a rendezvous with another carrier before boarding a bus to Oakland. Staying behind him, Oedipa watches him deliver various letters around an Oakland neighborhood before taking another bus to Berkeley. Oedipa again follows him and sees him go straight to the house of John Nefastis.
Abandoning her pursuit, Oedipa goes back to her hotel, where she finds a deaf- mute convention taking place in the lobby. In the lobby, a stranger suddenly grabs her and begins dancing with her as all the deaf-mutes pair up and begin dancing, although no music is playing. Oedipa feels shocked after she dances with a man for 30 minutes without colliding into anyone or falling out of step with other dancers. She thinks briefly that there may be some sort of deaf-mute conspiracy, although she brushes away that thought and just assumes that there was a conductor that she could not see.
One cultural feature of the 1960s was an enormous explosion of societal sub- cultures based on drug use. One of the more popular drugs at the time, LSD, was a particular type of hallucinogen known for inducing wild hallucinatory visions. We do not have reason to believe that Oedipa is herself taking acid, but we can see that she is beginning to have trouble maintaining her sanity in such a way as to make it seem like she is on drugs.
These problems with hallucination highlight the much more pressing problem of the ability to understand what is real and imagined. The novel suggests that the human mind has an extraordinary ability to create situations that seem so real as to be indistinguishable from truly external events. Nowhere is this seen more clearly than Oedipa's all-night excursion, a trip that is essentially pointless in its conception and useless on all practical levels. Indeed, Oedipa only ends the night even more confused than she has been. The problems of reality faced by Oedipa really become the same problems faced by the reader of the novel. We see many events through the eyes of Oedipa even though the novel is technically a third-person omniscient narrative. We have seen several instances in which Oedipa is connected to the reader, particularly in the necessity she feels to find meaning in a series of perhaps unrelated clues. Now, we feel connected to Oedipa in our mutual struggle to ascertain what is real. Alas, this is one difficulty that will only become more complicated as the novel progresses.
Whereas mystery books tend to solve the unknown through the gradual presentation of more clues that cast small amounts of light on the questions at hand, this book seems to expand the unknown each time it presents more clues. For instance, although Oedipa seems to make an enormous amount of headway when she finds a W.A.S.T.E. mailbox and carrier, the fact that the carrier goes to Nefastis' house confuses her even more. Her night of wondering around brings her to see many more clues, but they only confuse her all the more, particularly when she has difficulty determining what really happened and what was imagined. It can be argued, then, that from a structural standpoint, each additional piece of information only expands the amount of unknown; in other words, the more we know, the more we know how much we do not know.