In chapter 3, Atticus speaks with Scout about her first day at school. Scout says that she doesn't want to go back. She tells Atticus about her teacher, Miss Caroline, who told her to tell Atticus to stop teaching her how to read. Miss Caroline also punished Scout by striking her across her hand with a ruler. Atticus tells Scout,
You never really understand a person until you consider things from his point of view . . . until you climb into his skin and walk around in it.
In other words, Atticus suggests that Scout should try harder to empathize with people, including Miss Caroline. After all, Miss Caroline is new to Maycomb County and must be finding it hard to adjust.
In chapter 22, Calpurnia takes Atticus through to the kitchen to show him all of the gifts of food that the African Americans of Maycomb County have left for him to express their gratitude for the effort he put into his defense of Tom Robinson. In response, "Atticus's eyes filled with tears." He tells Calpurnia to pass on the message that "they must never do this again. Times are too hard." Atticus cries because he empathizes with the poverty of those who have left him the gifts, and also because he empathizes with how difficult their lives are. The fact that they are so grateful simply because a defense attorney has done his job properly indicates how seldom it is that they receive fair and equal treatment. Atticus is very aware of this injustice, and the gifts remind him that these African Americans have lived for so long with it and will likely continue to live with it for some time to come.
On the final page of the novel, Scout describes the events in a story Atticus has been reading to her, which seems to be about a boy ("Stoner's Boy") who is falsely accused of "messin' up (a) clubhouse." Scout says that the boy "hadn't done any of those things . . . he was real nice." Atticus replies, "Most people are, Scout, when you finally see them." It's very fitting, of course, that these should be the last words that we hear from Atticus in the story. They succinctly epitomize the main lesson that he has been trying, throughout the story, to teach his children, namely not to be judgmental but rather to try to empathize with people.