Among the most powerful and bizarre images in colonial discourse is that of the black cannibals. In Heart of Darkness the well-known theme is adopted in order to make the setting of the narrative more realistic. The best part of Marlow’s crew consists of cannibals who help him in his mission up the Congo River:
I don’t pretend to say that steamboat floated all the time. More than once she had to wade for a bit, with twenty cannibals splashing around and pushing. We had enlisted some of these chaps on the way for a crew. Fine fellows – cannibals – in their place. They were men one could work with, and I am grateful to them. And, after all, they did not eat each other before my face: they had brought along a provision of hippo-meat, which went rotten, and made the mystery of the wilderness stink in my nostrils. (67)
But how does Marlow know that these people are man-eaters in reality? Surely he does not see them practicing cannibalism since "they did not eat each other before (his) face". And in his whole journey he does not come across even a single instance of cannibalism. And when the boat has grounded to a halt on the bank and these "cannibals" are very hungry he wonders why do they not attack the whole crew: "I might be eaten by them before long" . He interprets their gestures, looks and murmurs as signs of their cannibalistic intentions, but this interpretation is not based on clear evidence. It seems that cannibals are defined not by the practices and customs which they have been observed performing – not, then, by their own deeds – but by the representations of European travelers and colonists.
Heart of Darkness is part of a colonial discourse in which the African is represented by the European as "savage", "exotic", "cannibal", "primitive" and so on. In Henry Stanley’s Through the Dark Continent, a similar line of representation and proof is followed. In his account of the experiences in Congo the author writes: