In the 2002 First Perennial Classic edition of To Kill a Mockingbird published by HarperCollins, this quote appears on page 33, three pages from the end of chapter 3. This quote introduces a theme of the novel, and the quote is repeated near the end of the book. Here it goes on to say "until you climb into his skin and walk around in it." Atticus is trying to teach Scout how to get along with people. Empathy is crucial to effective interpersonal skills, which Atticus, a brilliant lawyer and kind man, understands. Atticus urges Scout to be more tolerant of Miss Caroline, the new first grade teacher. Scout will be less angry at her teacher if she considers the events of the day from Miss Caroline's point of view. Being new to Maycomb, the young woman didn't understand some quirks of the community that others took for granted, and therefore she made what seemed like stupid mistakes.
At the end of the novel, when Scout walks Boo Radley back home after he has saved her life in the Halloween incident, she stands on his porch and looks at the familiar street from his perspective. She says it is enough to stand on his porch—not get into his skin (chapter 31, p. 321). She has learned empathy in many ways throughout the novel, from trying to understand black people's experience in Maycomb, to appreciating Aunt Alexandra, to accepting the friendship and protection of Boo Radley. Atticus's instruction and example has finally paid off.