What is the significance of the color blue in the novel, The Last Book In The Universe?

The color blue is significant because it serves as a symbol of hope. The first example of this is when Bean finds a blue plate, which stands out as something exotic and beautiful in her world, which is primarily gray and brown. Bean believes that anyone looking at the plate would have to love it, but her father, Charly, destroys the plate out of fear for the hope that it gives Bean; it will be easier to survive if she does not dream above her station. Blue may also be tied to the idea of Eden or luxury; the city is surrounded by a blue barrier, which does not allow the normals to come through. Spaz is also amazed when he learns that the sky is blue in Eden, since in the Urb--like everything else--is gray.