In chapter 14, what did Atticus mean when he said, "Cal's lights are pretty good"? How do readers know Atticus is correct in his judgment of...

In chapter 14, Scout asks Atticus about rape and he gives her a jargon-filled answer as a deterrent. Scout doesn't understand it very well, but she does ask why Calpurnia made her ask her father rather than simply answering her on the day they went to Cal's church.  Aunt Alexandra has a fit when she discovers this and must have told Atticus he should fire Calpurnia when Scout overhears him say the following:

"Calpurnia's not leaving this house until she wants to. . . Besides, I don't think the children've suffered one bit from her having brought them up. If anything, she's been harder on them in some ways than a mother would have been. . . She tried to bring them up according to her lights, and Cal's lights are pretty good--and another thing, the children love her" (137).

The lights Atticus is talking about has to do with Cal's intelligence, loyalty, and motherly experience. For example, it was actually Calpurnia who taught Scout how to write. In chapter 2, when Scout's teacher, Miss Caroline, discovers that Scout can read anything placed in front of her, the teacher gets angry. So, Scout starts to write a letter to Dill and her teacher tells her not to write. Scout responds by thinking the following:

"Calpurnia was to blame for this. It kept me from driving her crazy on rainy days, I guess. She would set me a writing task by scrawling the alphabet firmly across the top of a tablet, then copying out a chapter of the Bible beneath. If I reproduced her penmanship satisfactorily, she rewarded me with an open-faced sandwich of bread and butter and sugar. . . I seldom pleased her and she seldom rewarded me" (19).

The children learn in chapter 12 that Calpurnia taught her son Zeebo to read and write. They also discover that most black folks aren't literate because Zeebo, the church chorister, must lead the singing line by line. Honestly, of all the African American nannies that the Finches could have, they got the best in Cal. She's a great cook, she teaches the kids to read and write, and she takes care of the kids when Atticus is away on business. She should not be fired simply because Aunt Alexandra feels she should leave; and, it's good to know that Atticus stands up for her.