1. The first of the narrators is a man on board the Nellie who tells us about Marlow, who is the other narrator. There are five people on the Nellie, the Director of Companies, an accountant, a lawyer, the narrator, and Marlow. They are on the Thames River, and as the sun sets, Marlow begins to tell them a story about when he was a steamboat operator on the Congo River.
2. Marlow emphasizes that England was conquered by the ancient Romans.
3. Marlow means that people conquer other people who are different from them and always come up with some reason or idea that justifies the violence or injustice to themselves or others. Marlow is not justifying imperialism or colonialism; he is pointing out that people have made up excuses to justify it.
4. When Marlow was a boy, there were many unknown blank spaces on the maps. He wanted to go to and explore these places someday, but by the time he was grown up, they had all been "discovered" and colonized.
