In Chapter Fourteen of Harper Lee's To Kill a Mockingbird, perhaps the most significant event that provides insight to Atticus' character is the heated debate that develops between him and his sister Alexandra. Aunt Alexandra is a proper woman of the South and a welcome member of polite society, and she is extremely conservative about what she believes is acceptable behavior for her young white niece. When Alexandra tells Atticus that it's improper for Scout to go to Calpurnia's [black] church and that he should pay attention to this daughter who is growing up, Atticus is quick to make his position clear. While Scout listens unobserved, feeling "the starched walls of a pink cotton penitentiary closing in" on her (and is ready to run away "immediately"), Atticus stands up not only to Alexandra's criticism of his parenting skills, but also to his sister's inference that there is anything wrong with the children having a close association with Calpurnia—one that they have had for so very long. When Alexandra suggests that it's time for Calpurnia to "go," Atticus responds:

...Calpurnia's not leaving this house until she wants to. You may think otherwise, but I couldn't have got along without her all these years. She's a faithful member of this family and you'll simply have to accept things the way they are...

Atticus speaks first of Calpurnia not as reliable "help," but as a member of the family. In saying this, he announces that Calpurnia is his equal and will not be budged on the point. When Alexandra starts to argue, Atticus adds:

I don't think the children have suffered one bit from her having brought them up. If anything, she's been harder on them in some ways than a mother...she's never let them get away with anything, she's never indulged them...She tried to bring them up according to her lights, and Cal's lights are pretty good—and...the children love her.

Having listened to this conversation, Jem lets us know that he is aware of the difficulties Atticus is facing with the Tom Robinson trial. The reader can infer that based on Atticus' fondness and respect for Calpurnia—which is founded on character and not race—Atticus will treat Tom Robinson with the same respect and regard. Atticus, among the many traits he exhibits, is the children's moral compass. His defense of Calpurnia reflects the moral integrity Atticus lives his life by, and that which he shares by example with Scout and Jem.