Marlow's Psychological Journey

In the Heart of Darkness, Conrad's utilization of Marlow's diminishing consciousness reflects the lack of civilized behavior and the presence of savagery in the Congo.  Marlow exhibits a strong moral code early on, and attempts to maintain it as he journeys through the depths of the Congo; however, his experiences lead him to question everything he believes as he absorbs the monstrous conditions as a result of British colonization.  Conrad suggests that an individual's beliefs are essentially a reflection of his surroundings because when Marlow is around civilized behavior, he has no problem upholding his morals; however, in the Congo, his understanding of humanity is strained, questioned, and challenged.  Therefore,
the longer he spends in the Congo, the less he can connect to the rest of the world outside of the Congo.