Atticus is talking to Jack and says, "I hope and pray I can get Jem and Scout through it without bitterness, and most of all, without catching Maycomb's usual disease." The clue to this passage is in the next sentence. "Why reasonable people go stark raving mad when anything involving a Negro comes up, is something I don't pretend to understand.." This is discussing the theme of prejudice and dislike for people that are not like you. It is discussing the lack of tolerance and acceptance of people who are different. The parallelism comes into chapter 10 when Scout talks about how Atticus is "older" than the other fathers. How she and Jem don't "fit in" with the other children because of the differences of their family to the other children's families. Differences are not tolerated in Maycomb on any level and it doesn't matter if it is rich to poor, black to white, two parents or a single parent household.