Chief Bromden believes that the Nurse will sometimes turn on a fog that permeates the building, making it impossible for him to see. This fog does not exist, but Bromden relates it to the fog used in the army, where "you were safe from the enemy, but you were awfully alone" (130). This is exactly as he feels when the fog comes in the hospital, and shows his overall reaction to the ward in the line "you had a choice: you could either strain and look at things that appeared in front of you in the fog, painful as that might be, or you could relax and lose yourself" (131). This shows that Bromden has long given up on resisting the way things are in the hospital, he has instead given in to the restrictions; we see this in the repeated use of the word "control". The fog also represents how he has lost himself in his mind because he has given up. The hallucinations that accompany the fog and the increased amount of it as time goes on shows the growing intensity of the oppression he faces. It is not clear if the fog is induced by his mental condition or the drugs given to Bromden, but if it is the latter, this also shows the ability of Nurse Ratched to maintain control by clouding the thoughts of the patients.
The Combine is Chief Bromden's way to describe all the workers and the system of the asylum. The Combine is a hateful group, and Bromden observes them closely. The Combine represents the oppression that people feel from society and the "system". As the Combine inflicts certain regulations and boundaries, so too do the general public inflict pressure to fit in and blend with the "norm." Bromden often describes the Combine, along with many other parts of the hospital, as a machine. His use of mechanical imagery shows the oppression of individuality in the hospital, and symbolically, the outside world.
From the beginning, Christian symbolism permeates the novel. Ellis, a Chronic, is nailed to the wall, an obvious image of Christ's crucification. Ellis also tells Bibbit to be a "fisher of men" before they go on their fishing trip. Jesus said this to Peter (a fisherman). McMurphy, however, is the prominent symbol of Christ. The fishing trip is led by McMurphy, and he brings twelve men, symbolic of the twelve disciples. McMurphy continually sacrifices his well-being for the benefit of the others in the ward, which is comparative for the ultimate sacrifice Christ made by dying on the cross for the world's sins to be absolved. McMurphy, too, makes this ultimate sacrifice. McMurphy's shock treatments on the cross-shaped EST table can be viewed as crucifixion, and his death when Bromden suffocates him allows Bromden to escape.