Precis: das Heimlich und das Unheimlich, Two Sides of a Single Coin
The major argument Freud undertakes is tied up in his statement that "the uncanny is in some way a species of the familiar." The most grim and macabre instances of uncanniness come from things that are eerily familiar, yet at the same time strangely unknown. Freud discusses the frightening aspect of the double because of its similarity to the self (Doppelganger). This and other disturbing "unintended repetitions" of events or things in our lives cause us fear, even to the point that we can be afraid of being "excessively fortunate." We fear to know too much. The greater the deviation from the everyday (the less time between one seeing the "number 62" repeated, the amount of time between one making a prophetic statement and it becoming reality etc.) the more frighteningly uncanny something is.