There are so many different passages in the novel in which the children display their curiosity about the phantom neighbor, Boo Radley. Perhaps the most telling evidence of their imagination comes when Jem describes Boo to Dill in Chapter 1. Although Jem has never seen Boo, he has already decided what his neighbor must look like.
Boo was about six-and-a-half feet tall, judging from his tracks; he dined on raw squirrels and any cats he could catch, that's why his hands were bloodstained--if you ever ate an animal raw, you could never wash the blood off. There was a long jagged scar that ran across his face; what teeth he had were yellow and rotten; his eyes popped, and he drooled most of the time.
My favorite example comes on the night of Miss Maudie's house fire when Scout discovers a blanket wrapped around her shoulders. She has no idea how it got there, and when Jem and Scout assure Atticus that they have not moved from their spot in front of the Radley House, Atticus "grinned slowly" and revealed that "all of Maycomb was out tonight." When he told Scout that it was Boo who had warmed her with the blanket,
My stomach turned to water and I nearly through up when Jem held out the blanket and crept toward me. "He sneaked out of the house and--turn 'round--sneaked up and went like this!... If you'd just turned round, you'da seen him."