The title of Melville's novel was inspired by a mercurial sperm whale that lived off the coast of Chile near an island called Mocha. This whale became well-known among mariners, for its aggressive nature, and seeming ability to think, plan and carry out its attacks on targeted ships. Described as a "freak of nature" by writer Jeremiah Reynolds in a New York magazine, this whale had bested hundreds of sailors in attacks on various seagoing vessels over the years and become something of a maritime legend.
It is likely that the "man versus nature" conflict involving the whale Mocha appealed to Melville, who was writing in the same era as idealistic transcendentalists such as Thoreau and Emerson. This was a novel less concerned about westward expansion and slavery, issues that were being argued with less and less civility in more and more American homes and venues such as Congress (Harriet Beecher Stowe's anti-slavery novel Uncle Tom's Cabin inflamed the South during this same period)and more concerned with man's relationship to the natural world, particularly as the natural world was becoming more and more marginalized by the Industrial Revolution.