Echoes of the language used by Kurtz (and proof that Conrad did not need to look far to find models for his character) can be found in a letter sent by a Congo Free State district commissioner named Jules Jacques to one of his subordinates after learning that villagers had been severing vines to extract the rubber, so killing them, instead of merely tapping the vines as they had been instructed:
M. le Ched de Poste. Decidedly these people of [Inongo] are a bad lot. They have just been and cut some rubber vines ... We must fight them until their absolute submission has been obtained, or their complete extermination ... Inform the natives that if they cut another single vine, I will exterminate them to the last man.