Ahab's Obsession in Herman Melville's Moby Dick

Ahab, in Herman Melville's Moby Dick, is obsessed, at least neurotically so, perhaps to the point of being disturbed; he is incredibly foolhardy; but he does not seem to be out of touch with reality, and he has certain redeeming qualities that suggest he is at least partially sane.

These are some of his neurotic qualities, which those who might want to argue that he is insane could point to: He is obsessed with revenge against Moby Dick; he sometimes attributes malice to Moby Dick, an animal. (He may see himself as fighting against the entire universe, with Moby Dick as a sort of warrior of [hostile] nature, representing it as a soldier represents their country. He is willing to fight anything that seems hostile to him, no matter how inanimate or removed from human power to harm it--"I'd strike the sun if it insulted me.") Ahab risks the lives of his whole crew, including himself. He will do anything to catch and kill Moby Dick, offer (and give) any reward, threaten (and carry out) any punishment. He keeps himself apart from his crew until long after the Pequod leaves harbor. If he had been able to kill Moby Dick, that would not have brought his leg back. And as it happens, he fails to kill Moby Dick and his mission results in the death of himself and his crew.

Yet other qualities of Ahab suggest that he is not mad. He "has his humanities," as Peleg says. He protects and befriends the meek and insane Pip. He tries to make sure that the letter to the dead sailor on the Jeroboam is delivered.