In Joseph Conrad's "Heart of Darkness," the imagery of the earth flowing somberly under an overcast sky evokes a profound sense of foreboding. This description not only paints a bleak picture of the setting but also hints at an emotional and psychological journey into darkness. The landscape itself appears to reflect the turmoil and despair that the characters experience throughout their expedition.

The phrase "lead into the heart of an immense darkness" suggests that the journey is not merely physical but also symbolic, delving into the depths of human nature and the complexities of colonialism. This darkness represents the moral ambiguity and the inherent savagery that lurks within civilization, challenging the notion of progress and enlightenment against the backdrop of imperialism.