Chapter "The rifle cracked. Tom Johnson leaped, flipped over and crumpled on the sidewalk in a brown-and-white heap." (Lee This is a Loss of Innocence for Jem and Scout not only because they watch a dog get shot but also because it's their dad who shot it
You see life from a new perspective once you understand that other people are not thinking of you anywhere near as much as you believed they were, and they only care about your usefulness to them. They disguise it with manners, compliments or religious niceties but deep down we're all selfish.