Moby Dick chapter 9, help?

The second thing to notice is that Father Mapple tells us the moral of Moby-Dick (to the extent that it has any moral) before we’ve even gotten to Nantucket. Preaching on the story of Jonah and the whale, Father Mapple explains that Jonah couldn’t obey God because he couldn’t disobey himself. If that’s not a lesson for Captain Ahab (who, unfortunately, doesn’t hear this sermon), we don’t know what is.