A journey in literature can be used to demonstrate a variety of things. It is often used to signify a journey through life, "a fall from innocence , in novels like The Catcher in the Rye and The Red Badge of Courage. However, in the novel, Heart or Darkness, Conrad uses the journey both in its literal and figurative meanings. Most obvious is Marlow's journey to discover Africa, and the effects of imperialism. On a deeper level, it seems as if Conrad uses the journey to cloak Marlow's true journey into himself.
Throughout the bulk of the novel, Marlow is traveling through Africa and bearing first-hand witness to the effects imperialism can bring upon a place. Conrad describes the people and the scenery as Marlow travels deeper and deeper into Africa as becoming more and more uncivilized, or "savage as he puts it. In describing the people of Africa, Marlow is hiding the racist views of the times inside his novel. Also, Marlow notices throughout the novel the effects that imperialism has had on Africa. He sees how the imperial nations that have invaded the continent have overrun the area, imposing their own views on the native African inhabitants. It shows Marlow that all imperialists are not there for the bettering of Africa, but instead are simply greedy people on a power surge, looking for weaker people that they can easily dominate.
On a more figurative level, for Marlow, the journey up the Congo River to the 'heart of darkness' is reminiscent of Guido's journey into hell in Dante's Inferno, with literary allusion always present, through forms of intense imagery. The landscape takes on a hellish nature and the wilderness is personified. Death is omnipresent and this is reflected in the death imagery used to describe the cities of Brussels and London, the Congo region and Kurtz' station. Based on the racist views of the time, it is not surprising that Conrad describes the vast unknown