The presence of alienation in the novel is seen in how its characters are fundamentally separated from all social bonds and understanding of human connection. This helps to establish the estrangement, or alienation, that they experience themselves. A significant part of the Modernist vision of the work is this idea that there is an alienating condition that is part of the modern setting.
Naturally, Kurtz represents alienation. When he is removed from Europe and placed in a condition where his true nature is revealed, Kurts is estranged from what it means to be a human being. He stands outside of himself, doing what he previously could never consider or contemplate doing. "The horror, the horror" is almost an affirmation of this. It is a statement of how separated human beings can be alienated from one another and themselves. Marlow is also presented as an alienated figure. His retelling of the story and his entire condition on the Nellie is seen through the lens of alienation. His description as a "Buddha" figure is reflective of how separated he is from his fellow mariners, and one in which he is almost unreachable by anyone and to anyone. The condition of alienation is one that seems to be an intrinsic part in the definition of human beings.