Its manager, George Bailey (in an unforgettable performance by James Stewart), explains that the money is not in the building society’s vault; it has been lent to other people in the town.

In 2008, during the crisis that rocked the foundations of western capitalism, the author and Harvard professor Niall Ferguson published The Ascent of Money.

According to the standard picture of public expenditure and revenue raising, governments can only spend if they first gather money through taxes or asset sales or borrowing.

It also prevails in sections of the academy, where some economists are wedded to the idea of money continually circulating through the economy as a persistent element in a closed system.

Also known as the financephalograph, this heroically clunky contraption used real liquid, hydraulics and pipes to illustrate how Phillips thought a sealed, circular, money-fuelled economy worked.)

Without such a conversation (knowledgeably adjudicated by finance writers and journalists) citizens will forever be bit-part players in capitalism – the irresistible targets of participants with better information.

Saved 84% of original text.