Ishmael reports that Ahab could be seen the night of the storm in his own chambers, consulting several nautical charts of the “four seas,” and collating information on where Moby Dick had been spotted previously by other ships. Although Ishmael indicates that it might seem impossible to find a single whale among all the world’s oceans, Ahab nevertheless has a system wherein he looks at all the tracked locations of the whale over time, and uses them to predict his direction, or “line.” Ahab believes that, because his crew is now in the South Pacific, and because he thinks Moby Dick is not nearby, he and the crew must wait another year in order to catch Moby Dick in his preferred feeding grounds of the South Pacific.
This part of the novel, like some other sections, strains believability a bit—although Ishmael will note, later, that some whales tend to have predictable patterns of feeding and mating, and tend, therefore, to haunt the same parts of the same oceans. But, again, it seems especially unlikely that the Pequod, even with Ahab at the helm, could locate a single whale in all the world’s oceans simply by plotting out its previous sighting-locations on a map. Ishmael and Melville simply ask the reader to believe that this is possible, and in doing so imply a kind of connection between Ahab and Moby Dick.
Ishmael goes on to say that, when Ahab emerges from his cabin after looking at his charts, he often looks like a “man possessed,” and is so caught up in his scheme to find the white whale that he loses the ability even to talk to the other sailors. Ishmael closes the chapter by saying that, like Prometheus, the Greek titan who stole fire from the gods, Ahab also has something “picking away at his heart” (Prometheus’s punishment was to have a vulture pick away at his liver).
Another of Ishmael’s classical or mythological comparisons. Prometheus was a titan who defied the Greek gods to give fire to men and was terribly punished. Ahab seeks to face Moby Dick—immense symbol of God, or nature, or perhaps just a dumb brute—defying God or perhaps just common sense, and he too is punished by the need always pecking at his heart. Ahab believes that he is powerful enough to command a kind of vengeance on the seas, the way that God wields his vengeance over men on earth.