Then all at once, with terrible suddenness, the light about him shot upward with the noise of a loud splash; a frightful roaring was in his ears, and all was cold and dark. The power of thought was restored; he knew that the rope had broken and he had fallen into the stream. . . He opened his eyes in the darkness and saw above him a gleam of light, but how distant, how inaccessible! He was still sinking, for the light became fainter and fainter until it was a mere glimmer. Then it began to grow and brighten, and he knew that he was rising toward the surface—knew it with reluctance, for he was now very comfortable. What does the motif of light represent in the excerpt and in the rest of the story?