"As touching the ancient authors generally, as well as the poets here appearing, these extracts are solely valuable or entertaining, as affording a glancing bird's eye view of what has been promiscuously said, thought, fancied, and sung of Leviathan, by many nations and generations, including our own."

This line, which appears in the Extracts chapter, introduces the notion of interpretation right from the beginning of the story. The narrator, whom the reader eventually learns is Ishmael, offers a collection of descriptions from different eras which all depict the whale in a unique way. Showing the reader that there is no singular way in which to define and interpret whales allows Melville to imply early on that knowledge has its limits. Much like the world at large, the almost cosmic nature of the whale is beyond human understanding. 

"First: The uncertain, unsettled condition of this science of cetology is in the very vestibule attested by the fact, that in some quarters it still remains a moot point whether a whale be a fish."

In Chapter 32, Ishmael discusses cetology, the study of whales, in an attempt to scientifically define what a whale is. The argument that a whale is a fish, one that Ishmael ultimately supports despite Carl Linneaus’s widely accepted theory otherwise, reflects an impulse to view the world through an alternative, more interpretive lens. Ishmael is often wrong when he tries to make scientific claims about whales, and this tendency reveals that even the novel’s narrator is not immune from the limits of knowledge.

"How it was that they so aboundingly responded to the old man's ire—by what evil magic their souls were possessed, that at times his hate seemed almost theirs; the White Whale as much their insufferable foe as his; how all this came to be…all this to explain, would be to dive deeper than Ishmael can go."

At the end of Chapter 41, Ishmael marvels at the absurdity of Ahab’s voyage of vengeance and reflects on the nature of the crew who will ultimately strive to help him achieve his goal of killing Moby Dick. The way in which Ahab manages to convince the other sailors to embrace his cause, he argues, is “deeper than [he] can go,” an argument which highlights the impossibility of truly understanding the inner workings of others. 

"So ignorant are most landsmen of some of the plainest and most palpable wonders of the world, that without some hints touching the plain facts, historical and otherwise, of the fishery, they might scout at Moby Dick as monstrous fable, or still worse and more detestable, a hideous and intolerable allegory."

This line, which appears in Chapter 45 as Ishmael discusses famous whale stories, ironically calls attention to the function and meaning of the novel Moby-Dick as a whole. Melville’s tale of Ahab’s pursuit of Moby Dick does have an allegorical aspect to it for the reader, but Ishmael insists that, within the world of the novel, this interpretation is “ignorant.” The disparity between the reader’s understanding of the White Whale and Ishmael’s emphasizes the importance of perspective even beyond the limits of the novel itself.

"The more I consider this mighty tail, the more do I deplore my inability to express it. At times there are gestures in it, which, though they would well grace the hand of man, remain wholly inexplicable…Dissect him how I may, then, I go but skin deep; I know him not, and never will.”

Throughout the novel, Ishmael repeatedly tries to define the whale in clear terms, and each time, he faces the reality that he will never be able to fully know everything about the massive and elusive specimen before him. His eventual acknowledgement of this fact in Chapter 86 reflects his embrace of uncertainty, a worldview which ultimately influences the rest of the novel. Ishmael comes to embody a skepticism toward anyone who attempts to establish absolutes about the world around them.