Money is “a social agreement,” according to Frederick Kaufman, a journalism professor at the City University of New York. You and the cashier both agree that a $20 bill — a green piece of paper that any baby or dog wouldn’t hesitate to tear to shreds — is worth something, and this consensus imbues the bill with value. Eventually, babies get on board, as they’re taught the value humans have long ascribed to different types of currency; a value that’s socially constructed, but so deeply ingrained in our society that it feels silly to question.

This consensus has led Kaufman to crown money “the most powerful metaphor.” In his new book, The Money Plot, Kaufman unravels the myth-making that has underpinned financial transactions from bartering to bitcoin.