What does The horror The horror mean in heart of darkness?

In Joseph Conrad's "Heart of Darkness," the phrase "The Horror! The horror!" is uttered by Kurtz, a central character who confronts the darkness within himself and the brutal realities of colonialism. It encapsulates his profound realization of the moral and existential despair stemming from humanity's capacity for evil and the emptiness of civilization. This moment reflects the overarching themes of the novella, including the critique of Imperialism and the exploration of the human psyche's darkest aspects. Ultimately, it serves as a haunting commentary on the consequences of unchecked power and the abyss of moral ambiguity.