Describe the exchange between Marlow and his idealistic aunt, how well does Marlow's self description as a realist hold up over the course of the story?

With all formalities completed, Marlow stops off to say goodbye to his aunt, who expresses her hope that he will aid in the civilization of savages during his service to the Company, “weaning those ignorant millions from their horrid ways.” Well aware that the Company operates for profit and not for the good of humanity, and bothered by his aunt’s naïveté, Marlow takes his leave of her. Before boarding the French steamer that is to take him to Africa, Marlow has a brief but strange feeling about his journey: the feeling that he is setting off for the center of the earth. Marlow has a sense of what kind of exploitation goes on but he isn't ready for the depravity he sees in the Congo. Take, for example, "the Grove of death". Marlow is inspecting the sorry dilapidated station. He comes across a grove of trees full of sick and starving black laborers. They have become ill and, unable to work, are allowed to wander off and die. It is a picture of human cruelty and misery that Marlow had not experienced before. Marlow’s perception of humanity is changed as he proceeds through the heart of darkness, his previous sense of realism replaced with disillusionment.