Aunt Alexandra believes the Finch Family to be the finest of the "Fine Folks" of Maycomb County. In her mind, no Finch can do wrong--except, perhaps, for Atticus and the way in which he brings up his children. To Alexandra, the illustrious Joshua S. St. Clair is the most prominent member of all the Finches: A cousin, Joshua is a "beautiful character" and published author of a single "small volume" of meditations, and this overblown literary feat has vaulted him to the top of the Finch family tree. She attempts to instill pride of the family in Jem and Scout through Joshua, but Jem knows a little about him as well.
"Is this the Cousin Joshua who was locked up for so long?"
Atticus has no such illusions about the Finch family. His opinion of Joshua is a more realistic one and a 180 degree reversal of his sister's view. In truth, Joshua the writer was the family disgrace, a man with mental instability who had once tried to kill the president of the University of Alabama and had spent time behind bars.
"Why, Atticus said he went round the bend... Said Cousin Joshua wasn't anything but a sewer inspector... Atticus said it cost the family five hundred dollars to get him out of that one--"
The truth is not an acceptable remembrance for her own family's "gentle breeding," and "standing stiff as a stork," she angrily tells Jem that "We'll see about this." After Atticus received what must have been a thorough chewing-out by his sister, he sheepishly tries to explain to his children Alexandra's concept of "gentle breeding," and how they needed to start living up to her concept of Finch behavior. But Atticus soon gave up after he had reduced Scout to tears, and he told her to forget everything he had said. Scout realized that her father didn't have it in him to espouse Alexandra's strict moral codes.
I know now what he was trying to do, but Atticus was only a man. It takes a woman to do that kind of work.