In Joseph Conrad's "Heart of Darkness," the atmosphere of the room reflects a profound sense of heaviness and despair. The description indicates that the illumination is not merely dim but carries a weight of sorrow, suggesting that the environment mirrors inner turmoil. The evening's cloudiness symbolizes a loss of clarity and hope, emphasizing the emotional state of the character.

This imagery intensifies the mood, as it connects the external world to the protagonist’s internal struggles. The idea that "the sad light" has taken shelter on her forehead evokes a sense of burden, implying that she bears the weight of past experiences. Thus, the room becomes a metaphor for the character's psyche, filled with darkness and the overwhelming presence of longing and melancholy.