Final Rewrite Marlow, the speaker of the story, states that them going to Africa is no different than in previous years the Romans entering England. He describes the struggles that the Romans had to go through like the savage inhabitants, diseases, weather, and even to some it meant death. He says that the Romans were conquerors and their only goal was to rob other countries by brute strength, while the British were colonizers who tried to make changes for the better wherever they went. The monologue isn't very clear but to me it says that England was a dark place not too long ago.
Compared to the existence of the earth 1900 years ago was like yesterday. Also, technology hasn't changed much and there are many dark places still left on this earth. The things that are intense and seem most important in ones life are insignificant in time. He uses words like "a running blaze on a plain" and "flash of lightning in the clouds" to emphasize the quickness of time.
The commander sees England as a place like the men see Africa. It is a "sea the colour of lead" and "sky the color of smoke" which makes it a dark and gloomy place. There isn't much to do around as they are on the boat because they can't dock anywhere and there are "savages" that would probably sabotage their things if not kill them. Even though the journey might have been scary for them, the commander kept himself happy by thinking that if he survives the journey and gets back to Rome he might get a promotion. The young citizen goes on the trip to "mend his fortunes".
He goes out to see what England is like and is simply mesmerized by the power of the wilderness. He thinks that there really isn't a way to fight against it to survive even though you seem powerless. Marlow contrast the "conquerors" to the "colonists" by showing their reasons for exploration. The Romans were out to conquer the world and they were robbing countries of their land. Their strength rose from the weakness of others and they did what they could to get the most land possible. The Romans were lesser men by doing this.
The English at least had a reason to go to Africa. They were going to make improvements and attempt to colonize Africa. They were sacrificing their lives for this journey. Marlow shows that the wilderness really isn't a place for men to be. The immense size of the "darkness" makes the people powerless even though they believe they can better that place. By "colonizing" and trying to improve the quality of certain places people often do more bad than good.
The darkness provides many challenges for the civilizer's and it makes their conditions worse causing them to achieve little.