When Marlow talks of London being a dark place, the theme of civilization versus savagery comes into play. Marlow's aunt believes he is an emissary of light, being sent into the darkness. Marlow sees this darkness through the placing of heads on poles, for a man named Kurtz. All of this makes Marlow change his inner feelings of himself, which relates to the theme of the journey of the inner self. Marlow talks of when the Romans first came to Britain, and how they had actually brought some light into the somberness of London, and how one day that light may disappear. This relates to the theme of dark and light. As Marlow tells of his voyage deeper into the unknown, his capacity for self-control is tested. Kurtz seems to inhabit his every thought. While this is happening, the theme of a journey into the inner self is seen again. There are certain patterns in "Heart of Darkness"; one of these is the theme of "threes". There are three chapters, three women, three times Marlow breaks the story, three stations, three central characters and three views of Africa. Marlow indirectly suggests by referring to the Roman conquest, that the theme of colonialism has existed since the earliest times of human history. Colonialism is seen as one of the major themes in the book.
When Marlow talks of London once being a dark place, the theme of civilization versus savagery comes into play. The book implies that civilizations are created by the setting of laws and codes that encourage men to achieve higher standards. London itself is seen as a symbol of enlightenment. We see this through Marlow and how he tells his crew that the Romans had brought a light into the darkness of Britain. Marlow and Kurtz are two antithetical examples of humanity. Kurtz represents what every man will become if left to his own desires, without a
protective, civilized society. Marlow represents the civilized soul that has not been drawn back into savagery by his "heart of darkness"....