psychological significance of journey

Conrad sets Marlow through a physically exhausting journey through the river and Congo. Marlow's journey quickly becomes a psychological journey, by having to have morals. But as he goes farther and farther into "the heart of darkness" his emotions start to take over and his whole journey is at risk. As the narration of Marlow becomes more disorganized we begin to learn that he is over coming his need for such a stable life style and understands what is is like to live in the Congo. He becomes more sarcastic throughout and shows his change through his narration.