In Heart of Darkness, look at Marlow’s response to Kurtz. What other motifs in the novel can you connect to Marlow’s emphasis on his lack of restraint, the fact of his eloquence when he is actually “hollow at the core”? Examine Marlow’s feelings about Kurtz and the manager. What changes in attitude is Marlow experiencing? How does he feel about each of these men by the time they begin the journey back down the river and as that journey progresses?
One of the most important motifs that can be connected to Kurtz and the fact that he is eventually seen by Marlow to be "hollow at the core" is the role that civilisation plays in the novel as a guiding force that keeps characters on the straight and narrow. Marlow himself experiences the way that, in the heart of Africa, away from the West and so-called "civilisation," there is nothing to prevent him from doing hideous deeds should he feel the need. Even he at various points shows he is losing his grip on sanity. Note how he appeals to the understanding of the other passengers on the boat who are listening to his story:
You can't understand. How could you?--with solid pavement under your feet, surrounded by kind neighbours ready to cheer you or to fall on you, stepping delicately between the butcher and the policeman, in the holy terror of scandal and gallows and lunatic asylums--how can you imagine what particular region of the first ages a man's untrammelled feet may take him into by the way of solitude--utter solitude without a policeman--by the way of silence--utter silence, where no warning voice of a kind neighbour can be heard whispering of public opinion?
What prevents people from descending into insanity normally is the threat of the "policeman" and the "gallows and lunatic asylums." When these are removed and are replaced with "utter silence" and "utter solitude," without any "warning voice," humans are left to truly follow their own devices. This is what has turned Kurtz from a man of principles, a respected man who had a future, to, ultimately, a "hollow man," because he is unable to keep his ideals and beliefs untainted by the "utter solitude" into which he is plunged. At the end, Marlow realises that his ideals have been corrupted, and although he still retains an incredible eloquence, there is nothing at its core. This change has occurred because of the way that Kurtz has spent so much time in Africa that he has become unanchored from every aspect of civilisation.