Moby-Dick; or, The Whale is a novel by Herman Melville, first published in 1851. It is considered to be one of the Great American Novels and a treasure of world literature. The story tells the adventures of wandering sailor Ishmael, and his voyage on the whaleship Pequod, commanded by Captain Ahab. Ishmael soon learns that Ahab has one purpose on this voyage: to seek out Moby Dick, a ferocious, enigmatic white sperm whale. In a previous encounter, the whale destroyed Ahab's boat and bit off his leg, which now drives Ahab to take revenge.