Early in the narrative of To Kill a Mockingbird, the reader learns that the Cunninghams, though poor, are people of dignity. Or, as Atticus tells the children, the Cunninghams come "from a set breed of men," men who are too proud to take handouts, men who wish to carve out their own lives, men who think for themselves. Then, in Chapter 15 when the men come to the jailhouse where Atticus sits before the door and demand that Tom Robinson be handed over to them, Scout talks with Mr. Cunningham in her loyal attempt to diffuse the tension of the situation. Ashamed of having threatened Mr. Finch, Mr. Cunningham beckons the other men, saying "Let's get going, boys."
Of course, this change of mind and act of leadership on the part of Mr. Cunningham does not go unnoticed by Atticus. Comprehending that Mr. Cunningham is a reasonable man and one who thinks independently from the crowd, Atticus Finch trusts that the large Mr. Cunningham will make an excellent juror, for he will not be swayed easily by others, and he will consider all the evidence and testimony, hopefully, without giving in to his racial prejudice.