That inscrutable thing is chiefly what I hate; and be the white whale agent, or be the white whale principal, I will wreak that hate upon him. Talk not to me of blasphemy, man; I’d strike the sun if it insulted me. For could the sun do that, then I could do the other; since there is ever a sort of fair play herein, jealousy presiding over all creations.”

In Chapter 36, Captain Ahab calls the entire crew of the Pequod up to the quarter deck and explains that they are after a white whale by the name of Moby Dick, offering a gold doubloon as a reward for spotting him. Ahab becomes increasingly irate as he describes the loss of his leg and his desire for vengeance, despite the skepticism of those around him. This line in particular reveals that, subconsciously, Ahab is not just after the whale itself but rather the inscrutability it and its whiteness represents. His assertion that he would “strike the sun if it insulted [him]” reflects the sense of total control he wishes to reclaim by killing Moby Dick.

"God help thee, old man, thy thoughts have created a creature in thee; and he whose intense thinking thus makes him a Prometheus; a vulture feeds upon that heart for ever; that vulture the very creature he creates."

At the end of Chapter 44, Ishmael offers this reflection as he describes Ahab’s tendency to wake in the middle of the night in a fit of madness. The allusion that Melville makes to the myth of Prometheus emphasizes the internal sense of torture that Ahab endures in his pursuit of Moby Dick while also suggesting that this torture is ultimately self-inflicted. His feeling of woundedness and deep desire for revenge, Melville argues, are the causes of the madness that eats at his soul.

"This is the magic glass, man; I see my wife and my child in thine eye.  No, no;
stay on board, on board!--lower not when I do; when branded Ahab gives chase to Moby Dick.  That hazard shall not be thine.  No, no! not with the far away home I see in that eye!"

While Ahab appears as a vengeful madman for a majority of the novel, this moment, which occurs in Chapter 132, reveals that a hint of humanity still exists within him. Starbuck comes upon him looking rather defeated, and they have this exchange in which Ahab sees a vision of domesticity and family. The fact that he instructs Starbuck to stay aboard the Pequod while they pursue Moby Dick suggests that he regrets abandoning his family for the sake of the hunt, a response which starkly contrasts with his typical monomaniacal perspective. Despite this acknowledgement, Ahab feels that he must follow through with his hunt and decides to spare Starbuck rather than himself.