“A mob’s always made up of people, no matter what. Mr. Cunningham was part of a mob last night, but he was still a man. Every mob in every little Southern town is always made up of people you know—doesn’t say much for them, does it?”
In Chapter 16, Atticus talks to Scout that the mob from the previous chapter who intended to lynch Tom Robinson before the trial. He tells her a mob isn’t a group of faceless, nefarious individuals but human beings, people she knows. Read more about this quote in Quotes by Theme: The Coexistence of Good and Evil.
“Sunburned, lanky, they seemed to be all farmers, but this was natural: townfolk rarely sat on juries, they were either struck or excused. One or two of the jury looked vaguely like dressed-up Cunninghams.”
In Chapter 16, Scout observes that the jury appears to be made up entirely of white farmers—anyone else has been “struck or excused.” Comparing a selection of them to “dressed-up Cunninghams,” particularly after her experience with Mr. Cunningham and the lynch mob, suggests the jury is already prejudiced against Tom Robinson. At the very least, they are certainly not a jury of his peers, putting him at a disadvantage.
“‘Yeah, but Atticus aims to defend him. That’s what I don’t like about it.’ This was news, news that put a different light on things: Atticus had to, whether he wanted to or not. I thought it odd that he hadn’t said anything to us about it—we could have used it many times in defending him and ourselves.”
In Chapter 16, Scout eavesdrops on the Idlers’ Club—a group of old white men who spend much of their time hanging around the courthouse, sitting in on various trials—and learns that Atticus was appointed to defend Tom Robinson, not that he chose to do so. She’s surprised, given that she could have used this information; it would have helped while being picked on at school, for instance, if Scout could have told her classmates that Atticus had no choice. However, to Atticus, this point doesn't matter. The Idlers emphasize that Atticus intends to actually try and help Tom. This is crucial; Atticus wants to put together a solid defense, something that angers the racist people of Maycomb who would expect a white lawyer to put in zero effort to defend a Black client.