Harper Lee shows the character of Atticus through the language she chooses for him, by differentiating him completely from the townsfolk of Macomb. If you notice, Atticus is not only a well- educated man, but one who picks his words carefully in order not to belittle, nor offend, anyone.
When he is upset, as he is during the trial of Tom Robinson, he reflects the mentality of the people by repeating the common mistaken ideas that people have about their black neighbors. He appeals to the emotions of the people by clearly declaring how he, himself, accepts everybody as an equal and is willing to defend anybody whom he considers to be innocent. This, he does with words that appeal directly to the senses, as well as to the common sense of his audience.
He is measured, paused, eloquent, and not overly-complicated when he talks, despite of being one of the most intelligent men in Macomb. He is able to talk to just anybody regardless of social or educational level and change his mode to adapt to theirs.
In all, one can almost feel that Atticus is a being altogether alien to Macomb. His eloquence, his in-depth thinking, and the simplicity and sensible ability for speech make him someone who exudes tolerance, compassion, peace, and love, towards all.
Although Atticus Finch is possibly the most intellectual man in all of Maycomb, he is also presented as equally down to earth and a man of the people. He is an attorney and state legislator who runs unopposed each term, yet he is self-educated and accepts trade from his customers in lieu of cash. Through the eyes of his daughter, Lee describes the depth of her adoration as well as her frustration with Atticus' complex character. He offers words of home-spun wisdom--"It's a sin to kill a mockingbird" and "Climb into his skin and walk around in it"--that guide his children along a straight path, but he allows Scout to wear overalls instead of skirts, hoping that she will eventually see the light and take her first steps toward being a lady.
He is at heart a country boy who loves small town life and the people who go with it. His needs are simple: He walks to work, he plays the Jew's harp, and he grins when he glimpses his gift of pickled pigs' knuckles after the trial. Miss Maudie tells us that
"Atticus Finch is the same in his house as he is on the public streets."
Dolphus Raymond assures Scout that
"... your pa's not a run-of-the-mill man, it'll take a few years for that to sink in..."
He is not infallible: His client is found guilty and sentenced to death; he makes the near-fatal mistake of failing to escort his children to the pageant on Halloween; and he fails to see that it was Boo and not Jem who killed Bob Ewell. In Atticus, Harper Lee creates an everyman, a mortal who strives to live his life according to his conscience and to the high moral standards he sets for his children.