Harper Lee's introduction of Uncle Jack into Chapter 9 of To Kill a Mockingbird furthers the purpose of this novel's being a bildungsroman. For, in this chapter, Scout interacts with her uncle who disapproves of her use of crude language, one of her "stages." After her altercation with her cousin Francis, Jack, then, discusses her behavior as well as the upcoming trial of Tom Robinson with Atticus because Francis has repeated what his grandmother has said.
Privately, Atticus tells his brother that he feels there is little chance for Tom with the initial trial; however there is a "reasonable chance on appeal. Jack asks Atticus if he could not decline to defend Tom. Atticus, knowing that Scout is listening, tells Jack,
"Right. But do you think I could face my children otherwise? You know what's going to happen...and I hope and pray I can get Jem and Scout through it without bitterness, and most of all, without catching Maycomb's usual disease. Why reasonable people go stark raving mad when anything involving a Negro comes up, is something I don't pretend to understand...I hope they trust me enough...Jean Louis?"
As her father speaks confidentially with his brother Jack, Scout learns more about the calm rationalism of her father. Moreover, by overhearing her father, Scout is much more impressed with what he says and will take his words to heart about "Maycomb's usual disease."