Imagine a world with no need for money
One of the interview questions for economists at the Bank of England (years ago, when I was there), went: “Imagine a world with no money. Could there be inflation?” To which the ‘correct’ answer was ‘no’. You could see changes in the relative price of certain goods or services, but not in the general price level. And the inference from that: inflation is always and everywhere a monetary phenomenon. At that time, this was a thought experiment designed to illustrate