What significance lies in Marlow's references to maps? How do they represent the novella's frequent opposition between light and darkness?
Even as a child Marlow was fascinated by the "blank spaces" on maps, areas that hadn't been explored. He yearned to visit those exotic lands. As the blank places are explored and mapped, the maps become darker. Symbolically, Conrad is depicting the negative effects of European colonialism. The exploration, for instance, done in Africa was motivated because of a desire for ivory and rubber, not merely a pure curiosity about the land itself.
Conrad's light and dark motifs in the novel in effect offer an interesting use of such imagery. Most of the Europeans (whites) are not depicted in a positive sense because they, for the more part, are insensitive to the plight of the natives they abuse. Ivory itself becomes an evil because of what men will do to obtain it. Darkness, typically a symbol of evil, is a double image because it represents both the evils committed by the Europeans like Kurtz and the inherent nature of the Africans themselves. Without the intervention of the white men, the Africans do not demonstrate any evil qualities; therefore, the darkness here becomes a symbol of basic good. Conrad's use of light and dark, however, emphasizes the ambiguous moral nature of man. He foreshadows this quality with his first reference to maps.