What are some themes associated with "Empathy" in the novel "To Kill A Mockingbird?"Please provide textual proof and explain the author's view on...

As the greatest example of the similar theme of tolerance, Atticus teaches his children to empathize with others.  For instance, in Chapter 2 Scout commiserates with the embarrassment of Walter Cunningham when Miss Caroline asks him   lunch is because she does not realize that the Cunningham's cannot afford to send Walter with a lunch.  Scout, who is aware of their situation, explains to the reader that

If I could have explained these things [about Walter's family] to Miss Caroline, I would have saved myself some inconvenience and Miss Caroline subsequent mortification, but it was beyond my ability to explain things as well as Atticus, so I said,'You're shamin' him, Miss Caroline.  Walter hasn't got a quarter at home to bring you, and you can't use any stove wood.'

Later in Chapter 3, when Scout brings Walter home for supper and she criticizes his pouring syrup over his dinner, Calpurnia scolds her fiercely, telling her how impolite she has been:

'Don't matter who they are, anybody sets foot in this house's yo' comp'ny, and don't you let me catch you remarkin' on their ways like you was so high and mighty!'

Another example of the teaching of tolerance/empathy to the children is exhibited in Atticus when he instructs Scout to keep quiet about their reading of The Mobile Register at night as he does not wish to threaten Miss Caroline, who may believe that he feels himself a better teacher than she.  He also chides Jem, Scout, and Dill for harrassing Boo Radley, forbidding them to run into the Radley yard.

Even the lowly Ewells are to be shown tolerance, according to Atticus.  Even though Mr. Ewell breaks the law by hunting and trapping out of season, Atticus explains, he will not stop and at least he is feeding his poor children:

'Are you going to take out your disapproval on his children?'

Of course, two salient examples of the theme of tolerance/empathy occur with Atticus's chastisement of Jem for cutting the flowers of Mrs. Dubose and his accepting of the job of defending Tom Robinson.  He punishes Jem's destruction of Mrs. Dubose's flowers by making him read to the old woman; during this activity Jem begins to perceive her as a real person who is in a great deal of pain.  And, Atticus fights for Tom's acquittal on the charge of a rape that he did not commit.  He even positions himself in front of the jail door to protect Tom from a lynching by an angry mob.  Clearly, Atticus Finch is a much better Christian than his sister Alexandria with her missionary teas.  For, he always practices charity, not just when fashionable society is around.

Indeed, one of Harper Lee's concerns as a citizen of Monroeville, Alabama, was the inequity of the races.  She wrote this novel to expose the pettiness of those who do not empathize with others less fortunate, and to teach a moral lesson:  Everyone deserves the charity of others' hearts.