Heart of Darkness projects the image of Africa as "the other world," the antithesis of Europe and therefore of civilization, a place where man's vaunted intelligence and refinement are finally mocked by triumphant beastiality. The book opens on the River Thames, tranquil, resting, peacefully "at the decline of day after ages of good service done to the race that peopled its banks." But the actual story will take place on the River Congo, the very antithesis of the Thames. The River Congo is quite decidedly not a River Emeritus. It has rendered no service and enjoys no old-age pension. We are told that "Going up that river was like traveling back to the earliest beginnings of the world."
Is Conrad saying then that these two rivers are very different, one good, the other bad? Yes, but that is not the real point. It is not the differentness that worries Conrad but the lurking hint of kinship, of common ancestry. For the Thames too "has been one of the dark places of the earth." It conquered its darkness, of course, and is now in daylight and at peace. But if it were to visit its primordial relative, the Congo, it would run the terrible risk of hearing grotesque echoes of its own forgotten darkness, and falling victim to an avenging recrudescence of the mindless frenzy of the first beginnings.
These suggestive echoes comprise Conrad's famed evocation of the African atmosphere in Heart of Darkness . In the final consideration his method amounts to no more than a steady, ponderous, fake-ritualistic repetition of two antithetical sentences, one about silence and the other about frenzy. We can inspect samples of this on pages 36 and 37 of the present edition: a) it was the stillness of an implacable force brooding over an inscrutable intention and b) The steamer toiled along slowly on the edge of a black and incomprehensible frenzy. Of course there is a judicious change of adjective from time to time, so that instead of inscrutable, for example, you might have unspeakable, even plain mysterious, etc., etc.