What does Diana notice about the mural painted in the ceiling in Grand Central Terminal in the novel, Wish You Were Here?

In the beginning of the novel, Diana’s father restores a mural of the night sky full of constellations on the ceiling of Grand Central Terminal. Diana notes that the artist painted the entire mural backwards. “Instead of correcting it, though, my father was diligently reinforcing the error” (4). This sets up the entire trajectory of the novel. Diana is unhappy with her life but feels safer “reinforcing the error” by continuing on her path with Finn. She spends the remainder of the novel trying to process her mistakes and then correct them in an attempt to move forward on a new path.