What does the mirror symbolize in the kite runner?

The Kite Runner is a novel written by Khaled Hosseini and published in 2003.

Mirrors are mentioned many times throughout the novel. The mirrors in the story reflect others' mistakes, however, they do not mirror those of oneself as indicated in the following quote: "When we were children, Hassan and I used to climb the popular trees in the driveway of my father's house and annoy our neighbors by reflecting sunlight into their homes with a shard of mirror".