What is one of the themes in 'Moby-Dick' as indicated by the narrative's allegorical structure?

The theme of the quest for personal revenge is central to "Moby-Dick," particularly through the character of Captain Ahab. Ahab's obsessive pursuit of the white whale, Moby Dick, represents his desire to exact revenge for the loss of his leg to the creature. This theme underscores the destructive nature of vengeance, highlighting how Ahab's personal vendetta drives him into madness and ultimately leads to the downfall of himself and his crew.

The allegorical structure of the narrative allows Melville to explore deeper philosophical questions about obsession, fate, and human nature, positioning Ahab’s quest not just as a personal grudge, but as a broader commentary on humanity’s struggle against the unknown and the destructive consequences of singular obsession. The narrative suggests that the relentless pursuit of revenge can consume an individual, overshadowing all other aspects of life and leading to tragic outcomes.