Name a quote in Moby Dick that shows self-destruction.

The novel is
centrally concerned with Ahab's quest to destroy the whale, Moby Dick, at any cost, including
his own life and those of everyone around him. Ahab, a character so completely self-possessed
that he commands awe just by looking at him, will stop at nothing to kill this creature, which
is evil incarnate in his mind. He is willing to die and to sacrifice his entire crew and
anything else in his path in order to achieve his goal.

Chapter 36, "The
Quarter-Deck," is a good one to look into for utterances on this theme. I will offer two,
but you can find more there. In it, Ahab states:

I will
wreak that hate upon him [Moby Dick]. Talk not to me of blasphemy, man; I'd strike the sun if it
insulted me.

To "strike the sun" is a famous
quote from the novel. To strike the sun is the epitome of a suicidal act, as it symbolizes
attacking a far, far more powerful force, one sure to destroy you. This shows how little Ahab
cares about his own life as long as he can strike a blow against his hated rival.

In the quote below, also from chapter 36, Ahab reveals his purpose when he says
"this is what ye have shipped for." He also shows his obsessive intent to get the
whale at all costs:

Aye, aye! and I'll chase him round
Good Hope, and round the Horn, and round the Norway Maelstrom, and round perdition's flames
before I give him up. And this is what ye have shipped for, men! to chase that white whale on
both sides of land, and over all sides of earth, till he spouts black blood and rolls fin
out.

In chapter 37, "Sunset," Ahab
declares:

Swerve me? The path to my fixed purpose is laid
with iron rails, whereon my soul is grooved to run. Over unsounded gorges, through the rifled
hearts of mountains, under torrents' beds, unerringly I rush! Naught's an obstacle, naught's an
angle to the iron way!

In this quote we see again how
fixated Ahab is on the destruction of Moby Dick to the exclusion of anything
else.