How is "darkness" used as a symbol in Heart of Darkness?
In Heart of Darkness, the titular "darkness" represents various parts of reality, human nature, and the corruption of decency when faced with insurmountable obstacles. Marlow uses it regularly both in a literal sense -- "the starred darkness" -- and in a symbolic sense to show how the Congo affects people morally and ethically. He uses it most effectively in regard to Kurtz, who, in Marlow's view, has had his moral soul completely destroyed by some event, or perhaps a succession of events, in the jungle.
Kurtz discoursed. A voice! a voice! It rang deep to the very last. It survived his strength to hide in the magnificent folds of eloquence the barren darkness of his heart.
(Conrad, Heart of Darkness, gutenberg.org)
The bolded phrase shows up in varied form throughout the novel. Marlow refers to the dark heart of the jungle itself, of the darkness that eats away at his own moral core, and of what he sees as the destruction of Kurtz's soul. The only part of Kurtz to survive the Congo's destruction was his voice, which he used to force others to his will. The darkness ate away at his morality, but left the tools of his influence intact; Marlow is entranced by Kurtz even as he is disgusted by Kurtz's actions. Darkness symbolizes both the moral place where Marlow fears he will end up, and the attraction of greed and power, which overcame Kurtz.
According to most scholars, the use of darkness in Heart of Darkness represents the inherent evil (or dark side) in humanity. It is also linked to colonization, especially when involving the exploitation of people and natural resources.
Throughout the novel, Conrad shows the reader that appearances can be deceptive. Our first view of this is the map of uncharted Africa. Marlow is able to see that the continent, when drawn, is for the most part unknown. As the result, it appears white on the map. Through exploration, colonization, and exploitation, the rest of the continent will be charted and filled in, which will cause Africa to appear dark. This is in direct contrast to the perception that exploration brings "light" to a region. Here, Conrad is trying to illustrate the negative ramifications of colonization.
Conrad also uses light and dark to tell us more about the inner state of specific characters. Kurtz, a Caucasian man, has white skin, but also has the darkest and most depraved soul in the novel. In addition to this, the reader discovers through Marlow that the African natives are truly noble individuals.
Finally, Conrad closes with the idea that darkness is not strickly limited to a continent. Darkness of humanity can appear anywhere. Just like Kurtz, darkness can infect the soul of any person. In the closing of the novel, Marlow describes how some parts of England, even with its civility and enlightenment, are just as "dark" as other places on the globe.
Darkness is used as an indication of evil in this work, yet the target of this judgment remains unclear. On the one hand, the word darkness clearly reflects the Congo environment, with both its darker people and its darker surroundings The environment can be described as evil in the sense that the people are depicted as mysterious savages in need of the civilization of the European colonizers. However, this is only in reference to darkness as an outward quality. Another point of consideration is the use of darkness to describe something innate, something of the soul. In this sense, the word darkness and the meaning of evilness that it carries can be applied to the Europeans, who watch as villages are torn apart by the quest for ivory. They lie, they trick, they manipulate - all for the greed of wealth and hunger for power. All this goes to show the word darkness and the trait of evil in a separate light.