In Herman Melville's "Moby-Dick," the notion of greatness is intertwined with a darker aspect of human nature. The quote suggests that those who achieve remarkable stature often do so because of a profound inner turmoil or obsessive drive. This idea implies that ambition, while a necessary force for achievement, can also lead to a destructive path, demonstrating that greatness may come at a significant personal cost.

Melville warns the aspiring individual about the perils tied to relentless ambition. The assertion that "all mortal greatness is but disease" indicates that true success is frequently accompanied by suffering and sacrifice. Thus, young seekers of grandeur must grapple with the idea that their pursuits may lead to an internal struggle, raising questions about the value of their ambitions and the nature of true fulfillment.