How do you understand the white whale, Moby Dick in Herman Melvi

How do you understand the white whale, Moby Dick in Herman Melville's Moby-Dick?
【正确答案】：The white whale, Moby Dick, symbolizes nature for Melville, for it is complex, unfathomable, malignant, and beautiful as well. However, the whale represents only evil. Moby Dick, is like a wall, hiding some unknown, mysterious things behind. For the author, as well as the reader and ishmael, the narrator, Moby Dick is still a mystery, an ultimate mystery of the universe, inscrutable and ambivalent, and the voyage of the mind will forever remain a search, not a discovery, of the truth.