There was one strange thing about this wall of light. His father (he had already come to recognise his father as the one other dweller in the world, a creature like his mother, who slept near the light and was a bringer of meat)⁠—his father had a way of walking right into the white far wall and disappearing. The grey cub could not understand this. Though never permitted by his mother to approach that wall, he had approached the other walls, and encountered hard obstruction on the end of his tender nose. This hurt. And after several such adventures, he left the walls alone. Without thinking about it, he accepted this disappearing into the wall as a peculiarity of his father, as milk and half-digested meat were peculiarities of his mother.