Jung was writing about James Joyce's Ulysses, but his observation rings just as true for Haruki Murakami's 1Q84 when he wrote:
What is so staggering about 'Ulysses" is the fact that behind a thousand veils nothing lies hidden; that it turns neither toward the mind nor toward the world, but, as cold as the moon looking on from cosmic space, allows the dream of growth, being, and decay to pursue its course.
Two moons hang in the sky, and the reason for why that is so is revealed by Murakami in Book 2 of 1Q84. The second moon, which existed in a story told by a teenage girl who ran away from a cult, was brought to life by a cram school teacher who took that story at the behest of his editor and rewrote it into a bestselling piece of literature. The woman that this teacher, Tengo, has always loved finds herself looking at the two moons in the sky and remembering the boy she gave her heart to when they were both 10 years old.
At the same time Aomame is looking at the two moons, coming to terms with her new-found realization that she has spent her life loving Tengo, he is looking at those same two moons with the new-found realization that he has always loved her. He imagines that the moon has given Aomame the best thing it can give a person -- "pure solitude and tranquility".
That there are two moons gazing impassively down at the separated pair plays directly into Murakami's theme of duality. It's seen throughout this middle section of 1Q84 with the various couplings of characters and reflected situations. In one of the many expository speeches in this section, Jung is referenced:
Where there is light, there must be shadow, and where there is shadow there must be light. There is no shadow without light and no light without shadow. Karl Jung said this about 'the Shadow' in one of his books: 'It is as evil as we are positive ... the more desperately we try to be good and wonderful and perfect, the more the Shadow develops a definite will to be black and evil and destructive ... The fact is that if one tries beyond one's capacity to be perfect, the Shadow descends to hell and becomes the devil. For it is just as sinful from the standpoint of nature and of truth to be above oneself as to be below oneself.
Aomame, begins this section accepting her final, and most difficult, assignment. She is a vigilante assassin whose benefactor, the dowager, wants her to kill a cult leader who has been raping prepubescent girls. His victims include a little girl who is sheltered at the dowager's safe house for abuse victims but who mysteriously disappears.