In Chapter 3, Atticus says to Scout that somebody is never able to understand the actions of somebody else "until you climb into his skin and walk around in it." This is something that Atticus does throughout the book in regard to Bob Ewell, even when his own children are threatened. For example, in Chapter 27, Ewell is antagonising those around him in Maycomb and causing trouble, and in spite of Aunt Alexandria's concerns about what he might do, Atticus chooses to respond with his own advice of trying to imagine what Ewell has gone through and how he is feeling as a result:
"I think I understand," said Atticus. "It might be because he knows in his heart that very few people in Maycomb really believed his and Mayella's yarns. He thought he'd be a hero, but all he got for his pain was... was, okay, we'll convict this Negro but get back to your dump. He's had his fling with about everybody now, so he ought to be satisfied. He'll settle down when the weather changes."
Atticus therefore is a character who practices what he preaches. He tries to instil in his children that you can only fully understand somebody else when when you are able to "consider things from their point of view," and this is an approach he adopts in trying to understand why Ewell is acting in the way that he does. By seeking to discover the bigger picture and exploring the motives and reasoning behind actions, Atticus prevents himself from reacting in an emotional way to Ewell and what he does.