Arthur Radley and some other boys had engaged in some teenaged pranks years ago, and while the other boys had suffered some mild consequences and gone on to get decent educations and live normal lives, Arthur's father had placed him under virtual house arrest since that time. Legends and rumors had arisen in the years that followed: Arthur dined on squirrels, roamed the streets of Maycomb at night, and had one time stabbed his father with scissors. Miss Maudie, discussing this with Scout one day, expresses nothing but disgust for Arthur's dad, who she sees as a zealot who ruined his son's life in the name of religion.
There are just some kind of men who--who're so busy worrying about the next world they've never learned to live in this one, and you can look down the street [to the Radley house] and see the results.
Miss Maudie expresses sadness for Arthur, telling Scout that he was never anything but polite and well-mannered when she encountered his while he was still young. Lee uses the "mockingbird" metaphor twice in this novel; Tom Robinson, and Arthur Radley are both "mockingbirds" who have been "killed" by their own unforgiving, judgemental, intolerant community.