Having reread the first two parts of 2666, I’m reviewing my notes on it so far. I reiterate the conjecture on Borges’s direct influence on Bolaño with regard to the role of nightmares and dreams in the book. It is certain that Bolaño was influenced by Borges’s ideas on dreams, derived from Groussac and Coleridge and other poets. In the lecture of Borges on "Nightmares" (from the book Seven Nights, and also collected in Everything and Nothing), Borges mentioned that, although we might wish otherwise, in dreams what is important is not the images but the impressions produced by them: "The images are minor; they are effects." And also two ideas: first, dreams are part of waking life; and the other idea, the splendid one, the belief of the poets: that all of waking is a dream. Borges then mentioned that there is no difference between these two ideas. He gave some brilliant examples from literature and if I recall it right, an example in real life. Borges ended this lecture, first delivered in Argentina, with a speculation about the particular horror of nightmares, which is beyond the horror of the waking life, and which can be expressed by any story, a horror that has something more to it (the flavor of the nightmare).
Borges’s theological/supernatural speculation at the end of his lecture is also scary: "What if nightmares were cries from hell? What if nightmares literally took place in hell? Why not? Everything is so strange that even this is possible."
I think that these hypotheses by Borges are what Bolaño borrowed as frameworks for the dreams and nightmares permeating 2666. Nightmares as a reflection of the waking life ("reality"). Nightmares impinging on real lives.
A proof of this was the conspicuous image of the two mirrors which was both present in Liz Norton's hotel room in Mexico (in reality) and in her dream. It was clearly a nod to Borges who included this image in his story "The Aleph" and also in the above-mentioned lecture on nightmares itself where Borges said that all it takes are two mirrors to construct a labyrinth.
In Norton's room there were two mirrors instead of one. The first mirror was by the door, as it was in the other rooms. The second was on the opposite wall, next to the window overlooking the street, hung in such a way that if one stood in a certain spot, the two mirrors reflected each other.
This was how the double mirrors were described (in reality) and their vivid reappearance in Norton's nightmare made them more significant. Later on she wrote about them in a letter to the other two critics Pelletier and Espinoza ("I remember I thought about the hotel. In my room at the hotel there were two very odd mirrors that frightened me the last few days. When I felt myself dropping off, I barely had the strength to reach out and turn off the light.")
In "The Aleph" Borges suggested a metaphysical meaning for the mirrors:
Each thing (the glass surface of a mirror, let us say) was infinite things, because I could clearly see it from every point in the cosmos. I saw the populous sea, saw dawn and dusk, saw the multitudes of the Americas, saw a silvery spiderweb at the center of a black pyramid, saw a broken labyrinth (it was London), saw endless eyes, all very close, studying themselves in me as though in a mirror, saw all the mirrors on the planet (and none of them reflecting me), … saw in a study in Alkmaar a globe of the terraqueous world placed between two mirrors that multiplied it endlessly ...
After seeing a lot of images aside from the mirrors, "The Aleph" ended the passage thus: "I wept, because my eyes had seen that secret, hypothetical object whose name has been usurped by men but which no man has ever truly looked upon: the inconceivable universe. Near the end of "The Part About the Crimes" the image of the two mirrors recurs. There was an indication that the labyrinth created by the two mirrors contains the evil reflected in reality. That the book was a dying man's attempt to articulate the inconceivable universe in nightmares which come alive in dreams and in waking life.