Six Degrees of Separation
We should select any person from the 1.5 billion inhabitants of the Earth—anyone, anywhere at all. . . . He bet us that, using no more than five individuals, one of whom is a personal acquaintance, he could contact the select individual using nothing except the network of personal acquaintances. . . . Our friend was absolutely correct: nobody from the group needed more than five links in the chain to reach, just by using the method of your acquaintance, any inhabitant of our planet. . . .
—From the translated short story “Chains” by Frigyes Karinthy (1887–1938), Hungarian author, playwright, poet
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