Overview
In Chapter 68 of Moby-Dick, turns from the act of whaling to a naturalist’s inquiry into the whale’s outer covering. Ishmael opens by declaring that the question of what constitutes the whale’s skin has provoked genuine controversy among both whalemen and learned naturalists. He reports that the blubber—a dense, elastic layer ranging from eight to fifteen inches thick—is the only substantial covering that can be removed from the whale’s body, and he argues that it should therefore be regarded as the true skin. A second, infinitely thin, transparent membrane (resembling isinglass) does cover the body, but Ishmael dismisses it as merely the "skin of the skin," too delicate to deserve the title for so massive a creature.
The Whale’s Markings
Ishmael then examines the visible surface of the Sperm Whale, which is covered with fine linear marks resembling Italian line engravings. Seen through the transparent outer membrane, these marks appear to be engraved on the body itself. Some patterns, Ishmael observes, resemble hieroglyphics—ancient, undecipherable characters like those found on Egyptian pyramids or the carved palisades along the Upper Mississippi. Larger, irregular scratches also mark the whale’s flanks, which Ishmael compares to the glacial scraping marks that Louis Agassiz identified on New England coastal rocks. He speculates that these scars result from hostile contact between bulls of the species.
The Blanket Metaphor
The chapter’s title derives from the whaling term "blanket-piece"—the long strips of blubber peeled from the whale during processing. Ishmael finds the term poetically apt: the whale is "wrapt up in his blubber as in a real blanket or counterpane," or better still, like an Indian poncho slipped over his head. This insulating layer allows the warm-blooded whale to thrive in the freezing Arctic seas where human sailors, falling overboard, are found months later frozen upright in fields of ice. Melville contrasts the whale with cold-blooded fish, which "warm themselves under the lee of an iceberg," emphasizing that the whale’s survival depends on maintaining warm blood in hostile waters—a feat proven by experiments showing that a Polar whale’s blood runs warmer than that of a tropical human.
Philosophical Conclusion
The chapter closes with a philosophical exhortation that elevates the whale from biological specimen to moral exemplar. Ishmael credits the whale’s survival to "the rare virtue of a strong individual vitality, and the rare virtue of thick walls, and the rare virtue of interior spaciousness." He then directly addresses the reader: "Oh, man! admire and model thyself after the whale!" The injunction to "remain warm among ice" and "live in this world without being of it" transforms the blubber into a metaphor for spiritual self-sufficiency—the ability to maintain one’s inner warmth and equilibrium regardless of external conditions, much as the dome of St. Peter’s retains its own temperature in all seasons.