In Heart of Darkness, which explores a voyage deep into the Belgian Congo and back, themes of alienation, loneliness, silence, and solitude are prevalent. The story opens and closes in silence, with men anticipating a tale and then left to ponder once it ends. A key theme is the effect of extended isolation in a remote and harsh environment on individuals' minds. The doctor who examines Marlow's head before his journey to Africa cautions him about possible personality changes from a long stay in the country. Numerous characters in the novel experience the harmful effects of prolonged silence and solitude. For example, Captain Fresleven, Marlow's predecessor, transforms from a gentle soul into a violent man, while the Russian, who has been isolated on the River for two years, dresses strangely and speaks incessantly. However, the deepest impact of loneliness and alienation is observed in Kurtz, who, cut off from all civilizing influences, has forsaken reason and conscience, succumbing to his most base and savage instincts.