According to Yuval Noah Harari, Sapiens (2011, tr. 2014), language – e.g. for gossiping (https://wordpress.com/post/paulhhodson.wordpress.com/757) – allowed Homo Sapiens to cooperate in social groups of up to 150 individuals.
But… [h]ow did Homo Sapiens manage to cross this critical threshold, eventually forming cities comprising tens of thousands of inhabitants and empires ruling hundreds of millions? The secret was probably the appearance of fiction. Large numbers of strangers can cooperate successfully by believing in common myths…
Churches are rooted in common religious myths… States are rooted in common national myths… Judicial systems are rooted in common legal myths. Two lawyers who have never met can nevertheless combine efforts to defend a complete stranger because they both believe in the existence of laws, justice, human rights – and the money paid out in fees.
Yet none of these things exists outside the stories that people invent and tell one another.
(Rue de la Loi, Brussels, from Cinquantenaire arch, 2011)