One of the most significant symbols in the novel is the journey up the Congo River itself, which represents the descent into the heart of darkness, both literally and metaphorically. As Marlow travels further up the river, he becomes increasingly aware of the darkness and brutality that lies at the heart of imperialism, and he confronts the moral ambiguity and corruption of his own actions.
The character of Kurtz is also a powerful symbol in the novel, representing the destructive potential of unchecked power and the consequences of losing one's moral compass. Kurtz's descent into madness and his obsession with power and control illustrate the dangers of colonialism and imperialism and the destructive impact they can have on both the colonizer and the colonized.
"Heart of Darkness" continues to be a controversial and challenging novel, with some critics condemning it as racist and others hailing it as a masterpiece of modernist literature. Despite these debates, the novel remains a powerful and thought-provoking exploration of the human condition and the darkness that lies within us all.