Okay, in school we just finished "To Kill A Mockingbird" and we have a sort of questionnaire thing to do. One of the questions is "Who symbolizes the "gray ghost" and why?" I have my suspicions that it is Arthur "Boo" Radley but I would really like to make sure. Care to help?

What are the characteristics of the gray ghost? ... of Boo Radley? Are they similar?