Conrad's Heart of Darkness and Jung's Shadow.
Jung considered that an archetype that embodies the most archaic and obscure part of the human psychism and which represents the lowest part of the personality is the Shadow. The Shadow is everything that is primitive, savage and violent in the human nature.
It is also present in the every-day life where the desire for domination, for enslaving and the urge for power are the expression of the primitivism inside an unevolved nature, the Shadow, which we all carry deep inside our selves. It is the part within that has to be changed and that forces us to escape our own ignorance and allows us to evolve through conscience. The Shadow is the dark side of the ego that stores all the evil we are capable of. Every individual has deep inside a dark part heart of darkness. Some keep it hidden and never show its presence, but for others it is a way of life. .
Conrad presented it in Heart of Darkness, in Mr. Kurtz. Opposite to him is Marlow, maybe a representation of another archetype, the Self. .
He is seen as an "emissary of light" travelling into "the dark continent". Marlow's voyage is a voyage into the dark heart of man. Almost from the beginning of the book Kurtz is present near Marlow because he gets more and more intrigued by this character and it seems like the only goal of his voyage through the jungle has become to talk to this man. .
Mr. Kurtz was a very clever and successful man considered a genius and also envyed by some because his station was the most productive ivory station in the Congo. But once he reached the wild life in Africa he turned into a real savage finding the most inhumane and violent ways of assuring the production. He is the unique victim of colonization, the wilderness around makes him forget about every boundary that was part of his previous life. I say previous life because there are two different lives for sure. His transformation into the absolute evil, his decay into the evil within himself killed him.