In To Kill a Mockingbird, what does Atticus say that brought the mob to its senses?
In chapter 15, the Old Sarum bunch attempts to harm Tom Robinson. Fortunately, Atticus is waiting outside of Tom's cell. However, Jem, Scout, and Dill have followed Atticus and witness the mob surround him. Tensions rise after Scout runs out of their hiding spot into the middle of the men. Scout does not understand the dangerous situation but recognizes Walter Cunningham. After several failed attempts at gaining Mr. Cunningham's attention, he eventually acknowledges Scout and tells the men to go home. In the next chapter, Atticus elaborates on the dangerous situation outside of Tom's cell. He explains to his children that Walter Cunningham is a good man, but was simply caught up in the mob mentality the previous night. Atticus then tells Jem that it took an eight-year-old child to bring them to their senses last night. Walter Cunningham was able to view the situation from Atticus' perspective, which is why he told the mob to disband.
After that scary scene in chapter 15, Atticus sits down with the children in chapter 16 and explains what happened. Scout made Mr. Cunningham stand in Atticus' shoes that night in front of the jailhouse. Walter has children of his own, and Scout made him realize that he wouldn't want his children in a situation like that, either. Atticus says,
"'Mr. Cunningham was part of that mob last night, but he was still a man. Every mob in every Southern town is always made up of people you know. So it took an eight-year-old child to bring 'em to their senses, didn't it?'"
In To Kill a Mockingbird, the mob is brought to its senses somewhat by Scout recognizing one of the members of the mob and asking about that person's child. This sort of thing takes the anonymity out of the mob atmosphere. Recognition is identification. Once a member of the mob is made human again by simple recognition, the mob atmosphere is broken.