"He capered toward Bill, and the mask was a thing of its own, behind which Jack hid, liberated from shame and self-consciousness."

This was said when Jack first put on the mask with the red representing the blood and violence and the black darkness and impurity, and the white his innocence that he is desperately trying to get rid of. He puts the mask on and doesn't even recognizes himself anymore giving him the impression that he is a different person and removes the fear of killing and violence and gives him no shame in doing it (page 64)