Perhaps this subject is addressed best in Chapter 9 during the Finches' visit to Uncle Jimmy and Aunt Alexandra's house at Maycomb Landing during Christmas. Scout overhears a conversation Atticus is having with his brother Jack--or at least she thinks she does. It turns out that Atticus realizes she is listening, and afterward, he calls her name--her "scalp jumped"--and tells her to go to bed. It was information that Atticus wanted her to hear, but it would be many years before Scout would realize this. Atticus explains to his brother why he decided to take on the defense of Tom Robinson.
"But do you think I could face my children otherwise? You know what's going to happen as well as I do, Jack, 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... I just hope Jem and Scout come to me for their answers instead of listening to the town. I hope they trust me enough..."