Why does Moby Dick spare Ishmael

Melville's Ishmael seems also to be banished, with nowhere to go, getting through it all by sheer luck. In the Bible, God helps Ishmael survive in the wilderness, just as God helps in the book, all religious views aside. Throughout the story that Ishmael tries to convince the reader that a whale chasing a whaling ship really isn’t as farfetched as it may seem. In an extensive discourse on the biology of whales, he makes it seem almost plausible that a whale can be malevolent and know it is being hunted. In his view, the whale possesses a nearly human consciousness and is bent on killing Ahab. All in all, Ishmael's role in the book does not go much beyond that of narrator.