The fog and the Combine are two key concepts in the book "One Flew Over the Cuckoo's Nest" and they are specific to Chief Bromden - the narrator. The fog was his safety and the Combine was the Society. These two concepts symbolize the protest against the Big Nurse. Chief wanted to get out of the fog and the control of the Combine.

The fog is Chief's safety. He lost himself in it until McMurphy came.McMurphy pulled Chief out of the fog and finally the fog broke down.

The fog represents Chief's mental clarity. It comes when he feels unstable and moves away when he is balanced. "The more I think about how nothing can be helped, the faster the fog rolls in." (101). Chief considers the fog his safety, his escape. "They start the fog machine again and it's snowing down cold and white all over me...