Typically, conquerers would invade a nation or area and force the people to submit to their beliefs, government, and customs. In Heart of Darkness, this tendency is portrayed by “a woman, draped and blindfolded, carrying a lighted torch.” Much like how a group of people carries their beliefs and customs with them into lands they subjugate,
the woman brings with her a “lighted torch” into the “sombre - almost black” darkness. Historically, the reason for conquering other lands was to bring religion and civilization to them, thus bringing them out of the “darkness,” or lack of civilization. This was considered a just and dignified excuse, as shown by the woman’s “stately [movement].” To bring light to the darkness, one needs a source of light, such as a torch - and what better way to bring people out of their barbarous ways than to teach them your customs? The darkness itself is the natives of Africa and their uncivilized ways, while the dignified movement of the woman bearing a torch symbolizes the noble act of bringing the natives out of the darkness by giving them the beliefs and customs of the Europeans.
Over the course of the entire framed story, Conrad examines the most inhumane part of conquest - blindness. The woman in the oil sketch carries into the darkness her people’s customs and beliefs, but she does so blindfolded. Not only can she not see where she is going, she cannot see what harm she may be doing. Similarly, Kurtz and the European expeditions that set out to “civilize” the natives do not notice the harmful side effects of what they are doing - either from the highly unlikely chance that they were drawn into the lie of civilizing the natives or because they were blinded by their greed for ivory. Because they are blinded, they do not see how “the effect of the torchlight...was sinister.” Therefore, the purpose of the blindfold is extended: the Europeans can go into Africa and take ivory without feeling uncivilized themselves.
Emphasizing the dual nature of the European expedition and focusing on the blindness to the side effects of their actions augments the effect of the cruelty brought upon the natives. While the undetaking may have had good intentions in the beginning, the nature of conquest combined with the narrowmindedness of mankind belies any notion of civilizing the natives.