A foreboding tale of the perils and evils of Belgian Imperialism, Heart of Darkness commences with the arrival of the world-weary seaman Marlow, who seeks employment as a captain of a steamer to replace one who has died. Having procured his position thanks to his aunt's recommendation that he will be "an emissary of light," something resembling a lower apostle.
Ominously, when Marlow presents himself, there are two women knitting black wool sitting outside the office that contains a map on a wall that is printed in many colors. Significantly, Marlow refers to the yellow patch [yellow is a symbol of evil] in the center which is his destination. Other foreshadowing exists with the a chain gang that passes by with the "deathlike indifference of unhappy savages." More symbolism pertaining to evil is at the way station where flies buzz.
After Marlow departs on a French steamer, he is lulled into a depressive state by the slow journey.He talks of his youth and the map which contained one river that snaked through the land. He tells the others,
It had ceased to be a blank space of delightful mystery--a white patch for a boy to dream gloriously over. It had become a place of darkness. But, there was one river....it fascinated me as a snake would a bird--a silly little bird...the snake had charmed me.
After Marlowe switches to a steamer captained by a Swede, he gets his first glimpse of Africa and the ivory trade and the waste of train rails. It is here where Marlowe sees the chain gang.
Disturbed by this sight, Marlowe goes toward a grove of trees, avoiding an artificial hole, he goes into a ravine. But, he reaches the shade of the trees only to discover there are men there, diseased and starving. One crawls to the river to drink. As Marlowe looks around, he realizes that this is where some of the workers have "withdrawn to die." Representative of an Inferno, this grove of trees is where the natives suffer and die while the imperialists come to exploit both the inhabitants and the natural resources. The grove of trees is symbolic of the extermination of native cultures when the imperialists exploit a land. So, too, are the evil practices of the Belgians exposed and symbolized--the "darkness" of exploitation and subjugation alluded to in passages that precede the sight of the grove.