Paul didn't have any friends in the front now, so he was very alone. " Years and months can take nothing from me any more. I have nothing to be lost." He wished that he could finish this life fast, and didn't care what result it was. He had the worst preparation for that; he didn't care anything. At last, suddenly, a bird's sing caught his attention. It gave him some meaning in life. In the world, still there is some beutiful things that he cared about it. This aspired his survival hope. So in this story, the bird is a symbol which give him the new meaning in life.