What exactly is the symbolism of the cemented hole in the tree in To Kill a Mockingbird?This is in Chapter 7, where Nathan Radley cements the hole,...

I don't believe Harper Lee had any underlying symbolic motives
concerning the Radley oak tree in To Kill a Mockingbird. The tree and its
knothole simply served as the secret message conduit between the children and Boo Radley. Boo's
brother, Nathan, apparently observed either Boo or the children reaching into the knothole, and
decided to investigate. He cemented the knothole not because the tree was sick, but in order to
keep his brother from having any further contact with Jem and Scout. Jem discovered that Nathan's
story about the tree being diseased was a lie when Atticus pointed out that it appeared perfectly
healthy. I suppose the act of cementing the knothole--a kind of symbolic heart of the tree--could
represent Boo's family's cold-hearted nature in general.