How is the need to survive illustrated in the book?

Perhaps typical of a castaway's survival story is the theme of the power of the will to survive and even the power of life to perpetuate. Early on in his castaway ordeal, once Pi had accepted that his family was probably dead and the rescue ship was not coming to pick him up, he had to make a decision whether to strive to live or give up. He chose to fight for his life. Pi even says in his story that he did not know how strong his will was until he faced this crisis. His will to live gave him the power to do things he would have never imagined himself doing such as catching and butchering fish and turtles, taming a hungry tiger and even at the point of greatest desperation eating human flesh. Pi's will often waned. He even hit a low point where his physical strength was completely gone; he had gone blind and could not even provide food for himself or Richard Parker. He had resolved to die. Even at those moments—like the one when he wrote in his journal that tomorrow he would die—his will and the power of life to prevail kept him alive even when his body and mind did not want to continue.