While the character of Calpurnia, who substitutes for the housewife in the Finch home and acts as the nurturer and teaches Jem and Scout good manners and reinforces correct behavior, it is Miss Maudie of Harper Lee's To Kill a Mockingbird who performs the distinct maternal role of reinforcing the moral lessons that Atticus Finch wishes to teach the children in the heartfelt and sympathetic way that only a mother can. In short, she is the heart that belongs to the rational statements and actions of Atticus Finch.
For instance, it is Miss Maudie who drives home to the children the meaning of Atticus's pronouncement that it is a sin to kill a mockingbird as she explains to Jem and Scout why their father has cautioned them so:
Your father's right....Mockingbirds don't do one thing but make music for us to enjoy. They don't eaat up people's gardens, don't nest in corncribs, they don't do one thing but sing their hearts out for us. That's why it's a sin to kill a mockingbird.
Earlier, in Chapter 5, Miss Maudie also clarifies the case of Boo Radley and gives the children a reason not to bother Boo that appeals to their emotions--as a mother does--which affects them deeply, convincing them of the admonitions of Atticus by explaining what "a sad house" it is in which Boo resides, and if he is not crazy, he should be because
"The things that happen to people we never reall know. What happens in houses behind closed doors, what secrets--:
So many times, Miss Maudie provides the comforting heart of the mother that softens the harsh rationality of the father. For instance, while they have overheard Atticus tell his brother that he could not face his children if he did not do all he can to defend Tom Robinson, they are yet confused by the harsh words of the townspeople. But, Miss Maudie puts everything into perspective, as a mother often can, by explaining the character of Atticus. In Chapter 24 when she speaks with Aunt Alexandra, the children overhear her say,
"Have you ever thought of it this way, Alexandra? Whether Maycomb knows it or not, we're paying the highest tribute we can pay a man. We trust him to do right....the handful of people who say a fair trial is for everybody....The handful of people in this town with bacground...."
That Scout and Jem have instilled in them the lessons of Atticus by means of the tender understanding of the motherly Miss Maudie is evinced in Scout's words of the final chapter:
Atticus was right. One time he said you never reall know a man until you stand in his shoes and walk around in them. Just standing on the Radley porch was enough.
Atticus Finch imparts many lessons to his children, but it is the Miss Maudie who takes their hearts and brings them to the "porches" of understanding.