The Uncanny is related to what is scary. It arouses dread and horror. What distinguishes "the uncanny" from what is otherwise generally frightening?
"The uncanny is that class of the frightening which leads back to what is known of old and long familiar."
How does the familiar become frightening? That is what Freud wants to investigate
The German psychologist Jentsch thought that uncanniness resulted from intellectual uncertainty. Freud thinks this is incomplete.
Freud explores the etymology of the word unheimlich and its opposite heimlich. On the one hand, heimlich means that which is familiar and congenial, and on the other, that which is concealed and kept out of sight. "Unheimlich" is used as the contrary of the first definition but not the second. Everything is unheimlich which ought to have remained concealed but has come to light.
One manifestation of the uncanny can be found in the example of automata, where inanimate creatures are thought to be alive. Think wax figures or statues or robots or puppets or dolls. Epileptics strike us this way too, because their motions are involuntary and mechanical.
Freud begins his analysis of "The Sandman". The story certainly contains an automaton, namely Olympia; however, Freud is more interested in Nathaniel's childhood memories of the sandman Coppelius.
What is uncanny is the fear of being robbed of one's eyes. This fear occurs in children and continues into adulthood. It is associated with the dread of being castrated. Notice how Hoffman juxtaposes the anxiety about losing eyes against the father's death. Also notice how the Sandman always appears to disturb Nathaniel from love. The Sandman symbolizes the dreaded father who threatens to castrate the son.
Next Freud turns to the theme of "the double". The double for Otto Rank was originally an insurance against the destruction of the ego. This starts in the primary narcissism of childhood. When the child grows up, the double takes a different guise. Instead of assuring immortality, the double foreshadows death. This double acts as an observer and critic of the ego, our conscience. "There are also all those unfulfilled but possible futures to which we still like to cling in phantasy, all those strivings of the ego which adverse external circumstances have crushed, and all our suppressed acts of volition which nourish in us the illusion of Free Will."
"The quality of uncanniness can only come from the circumstance of the 'double' being a creation dating back to a very early mental stage -- long since left behind, and one, no doubt, in which it wore a more friendly aspect. The 'double' has become a thing of terror, just as after the fall of their religion the gods took on demonic shapes."
There is a compulsion to repeat that goes back to our instinctual impulses. Whatever reminds us of this is perceived as uncanny.
Freud also talks about the uncanniness of the "evil eye". This relates to a principle of mind he calls the "omnipotence of thoughts", harking back to animism, spiritualism, magic powers. The uncanny triggers those primitive memories of animistic mental life within us.
The uncanny, psychoanalysis teaches, consists of the return of something familiar and old, now perceived as strange, because we have repressed it.