A running theme in is that man is savage at heart, always ultimately reverting back to an evil and primitive nature. The cycle of man's rise to power, or righteousness, and his inevitable fall from grace is an important point that book proves again and again, often comparing man with characters from the Bible to give a more vivid picture of his descent. symbolizes this fall in different manners, ranging from the illustration of the mentality of actual primitive man to the reflections of a corrupt seaman in purgatory. ....