Fourth, Marlow is asked to sign "some document" that ostensibly contracts him to not reveal "any trade secrets," but figuratively suggests the selling of his soul to the Devil. (As the Manager of the Central Station will later remark about Africa, "Men who come out here should have no entrails.") As the Devil seeks human souls to overthrow God in Heaven eventually, the Company is metaphorically seeking to acquire the souls of as many Europeans as possible to make greater profits.
Fifth, when Marlow is examined by the Company's Doctor, he learns that many Europeans who venture to Africa become mad: When the Doctor begins measuring Marlow's skull, the reader infers Conrad's point that European "science" and "technology" (even with a science as ludicrous as phrenology) are no match for the power if the jungle. When "civilized" Europeans go to Africa, the restraints placed upon them by European society begin to vanish, resulting in the kind of behavior previously seen in Fresleven. Later in the novel, when his anger begins to grow after finding all of his gear damaged by the porters, Marlow ironically remarks, "I felt I was becoming scientifically interesting."
Also worth noting is the abundance of white and dark images in these opening pages of Marlow's narrative. The Congo is described as a "white patch" on a map, Fresleven was killed in a scuffle over two black hens, Brussels is a "whited sepulcher," the two women knit black wool and the old one wears a "starched white affair," the President's secretary has white hair, and the Doctor has black ink-stains on his sleeves. Many critics have commented (sometimes inconclusively) on Conrad's use of white and black imagery; generally, one should note how the combination of white and black images suggests several of the novel's ideas:
The Company claims to be a means by which (as Marlow's aunt calls them), "emissaries of light" can bring civilization to the "darkness" of Africa, which is done by denoting Brussels as white and the Congo as white.
The White men in the novel (particularly Marlow and Kurtz) will be greatly influenced by their experiences with the Africans.
Although the Company professes to be a force of "White" moral righteousness, it is actually "spotted" with "black" spots of sin and inhumanity, and the corpses of the black natives that are found throughout the Congo.
