How does Marlow evolve as a character throughout Heart of Darkness?
Initially, Marlow tells his story in retrospect and is described as a "meditating Buddha," which illustrates his wisdom and enlightenment. When Marlow was a young man, he wished to travel to Africa to visit the "blank spaces" on the map. Marlow was intrigued with the enigmatic atmosphere surrounding the unknown. He joined the Company, which traded ivory from the Congo. Throughout Marlow's journey, he witnesses the inefficient, insincere employees of the Company. Marlow began his journey with certain idealistic impressions of European civilization and held onto the naive belief that Europeans were bastions of civility and morality. However, Marlow's perception begins to change after he gradually witnesses the chaotic nature of the Outer and Central Stations. Marlow's interactions with important employees reveal the debased nature of the Company and are an indictment of imperialism. The Manager is depicted as a scheming liar while the Accountant is portrayed as a greedy, prejudiced individual.
As Marlow continues his journey into the middle of the Congo, he rests his confidence on the mysterious Mr. Kurtz. Marlow is fascinated by the stories of Kurtz's success and hopes that Kurtz will turn out to be a benevolent ambassador of European civilization that will justify the Company's goals. However, Marlow discovers that Kurtz is a tyrant, who rules over the Natives as a god. Kurtz has abandoned his philanthropic ideals in exchange for power and influence. By the end of Marlow's journey, he gains insight into the "heart of darkness," which describes humanity's inherent wickedness as well as the unknown Congolese jungle. Marlow evolves from being a naive, impressionable young man, to a jaded, insightful individual, who has experienced the worst of human nature. Marlow truly understands that "The mind of man is capable of anything - because everything is in it, all the past as well as all the future."
There is a definite sense in which Marlow changes dramatically as a result of his experiences with Kurtz and what he learns and witnesses. In one sense, Marlow, by the end of the story, seems to have much in common with the ancient mariner in Coleridge's "Rime of the Ancient Mariner," in the way that he seems fated to talk about and share what has happened to him. Note how Marlow describes his feelings and attitudes towards life after he returns to Europe from Africa, finding himself once again in the "sepulchral city" which he went to before accepting his commission, with people who continue to "dream their insignificant dreams":
They treaspassed upon my thoughts. They were intruders whose knowledge of life was to me an irritating pretence, because I felt so sure they could not possibly know the things I knew... I had no particular desire to enlighten them, but I had some difficulty in restraining myself from laughing in their faces, so full of stupid importance.
Marlow's character therefore irrevocably changes because of the "heart of darkness" that he witnesses in the character of Kurtz, and this is of course strengthened by the recognition that this "heart of darkness" is in all humans. Marlow glimpses a hidden truth, and, to a certain extent, he is unable to re-enter normal life once again in the same way precisely because, having seen the truth about the human condition, he cannot participate in the same "meaningless" activity that he sees everybody else engaging in.