Symbolism, Imagery, Allegory
In Part 7, Chapter 29 of Doctor Zhivago, Yuri Zhivago sees a young man with a massive head wound being led into a military car. The soldier seems to be obsessed with putting his hat on straight, even though it's upsetting his bandages and causing him pain. As the narrator tells us, "The cap kept falling off the student's bandaged head. Instead of taking it off and carrying it in his hand, he would straighten it and pull it down further, to the detriment of his dressed wound, and the two Red Army men who helped him" (7.29.12).
For Zhivago, this situation symbolizes the total ridiculousness of revolutionary thinking. To put it simply, it's all about style over substance, since the kid is more worried about looking proper than taking care of a life-threatening injury. The narrator gives us Zhivago's thoughts directly: "In this absurdity, contrary to common sense, there was something symbolic. And, yielding to its significance, the doctor also wanted to cry out both to the boy and to the people in the car that salvation lay not in faithfulness to forms, but in liberation from them" (7.29.30).
In other words, Zhivago wants to tell this boy that he'll never be free if he remains so obsessed with outward appearances. The key to freedom is freeing yourself from these concerns, not giving in to them.
And by the way, kudos to Pasternak for straight-up telling us that the soldier's hat is a symbol. It's makes our job a lot easier.