Moby-Dick contains many of the themes that fascinated the Romantics. One is the struggle between heroic, ingenious man, symbolized, however imperfectly, by Ahab, and the raw, fearful power of nature embodied by the whale. This struggle contains a religious element as well. Does the whale act out of his own power, or is he simply an agent of God's will? Either way, Ahab is determined to risk his life, and that of his entire crew, against the awesome power of the creature. The theme of natural power is also conveyed in the different imagery assigned to land and sea. The land is nurturing and good, while the sea is dark, powerful, and even evil:
As the appalling ocean surrounds the verdant land, so in the soul of man there lies one insular Tahiti, full of peace and joy, but encompassed by all the horrors of the half known life. God keep thee! Push not off from that isle, for thou canst never return!
Some Romantics thought that life was a struggle "sturm und drang" that should be embraced, and the battle between Ahab and the whale, and the Pequot against the sea is a compelling one. The book is full of other themes that fascinated the Romantics, including violence and horror, exoticism and the occult (for example, in the persons of Queequeg and Fedallah, respectively,) madness, and questions about religion.