How to Learn to Love Your Doppelganger

What are you doing running through the streets in your underpants?” asks Tyler Durden in the movie Fight Club. “We both use that body.” He is addressing his unnamed doppelganger (German for “double walker”), whose life he has gradually usurped. The movie, a smash hit grossing $100 million, is just one recent example of our long-standing fascination with the idea of double selves, which stretches from ancient Egyptian and Norse mythology, through German folklore (in which it was considered a harbinger of death), into the hands of Edgar Allan Poe, Groucho Marx, and Brad Pitt.

Freud was one of the first to attempt to treat doppelgangers scientifically, calling them the “return of the repressed.” He argued that they are an