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Explicitly quoted at the opening of the episode as the famous 1848 work that begins 'A spectre is haunting Europe'

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Referenced as an example of proto-communist ideas, described as Thomas More's vision of a society where people share property at the turn of the 16th century

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Referenced as containing the description of the early church where apostles sold possessions and gave to anyone in need, cited as a prototype of communist society

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Referenced when discussing how Marx's language is 'shot through with the idea that there are supernatural entities' like vampires and bloodsuckers