The Double (n.) is a former split-off aspect of the ego that, in an uncanny experience, returns to harass it, leading the subject to experience themselves as something familiar yet other, as out of sorts or out of 'place', as fragmented, disturbed, and de-familiarized.
The Double (n.) is the idea that after the collapse of their religion, the Gods turned into demons.
The Double (n.) covers lookalikes, shared minds, confused identity and the recurrence of the same traits or names over generations: a doubling, dividing and interchanging of the self.
The Double (n.) was first an insurance against death, an energetic denial of its power; once narcissism is surmounted it reverses into the uncanny harbinger of death.
The Double (n.) became a thing of terror as the gods turned into demons when their religion collapsed: uncanny because it dates from a long-surmounted stage.
The Double (n.) met by chance in a mirror can go unrecognized and simply disliked, perhaps a trace of the archaic reaction that feels it uncanny.