The protagonist Marlow believes that: “the mind of man is capable of everything, because everything is in it, all the past as well as all the future” (109) . The basis of Heart of Darkness is Marlow's physical journey up the Congo River to meet Kurtz. The main character Marlow goes through many physical and psychological changes from the beginning to the end of the story. Marlow is innocent enough at first as he travels up the river, gets closer and closer to Kurtz, and as he gets closer and closer he learns more and more about the hearts of men and the darkness. When he finally reaches Kurtz, Marlow's perception is obstructed and he, physically and psychologically, does not know where he is. When Marlow is in The Themes, he talks about the "evils" he experiences while there and how he worked to transport ivory down the river. . In Victorian times Africa was called the “dark continent”. At the beginning of the book, Marlow explains that London, although at the time the richest and most populated city in the world, was also at one point the "dark city". This concept is similar to Conrad's tale of the Belgians conquering the savage Africans. Darkness is everywhere, even in the hearts of “civilized” people. It appears often and is explored through the characters. Marlow is removed from society in the jungles of the Congo where he is forced to adapt to extreme conditions both physically and mentally. These conditions force Marlow to change the way he thinks about things historically and geographically. To better understand Marlow's mental journey and how the challenges in the jungle changed him, it is necessary to inspect the mind through the method of psychoanalysis. There are three different types of psychoanalysis at the heart of the paper, unlike Kurtz, he himself chose to endure the Id rather than allow himself to be controlled by it. As a sort of reward, Marlow lives through the desires of the id and returns to the city as an enlightened and wise man, although he returns as a mental wreck. Marlow went through three mental phases during his journey to Africa that changed him forever. . He became wise. He not only experienced new cultures, but completed an extremely tough mental journey. At the end of this journey he experienced extreme changes in his psyche that occurred during his journey to and from the Congo. He begins as a naive sailor longing for adventure, representing the Superego. Then, when he isolated himself in the Congo, away from the restrictions of society, his identity instincts emerged. He has the courage to continue and when he returns to society, his ego balances his id and superego.