Economists have know for 500 years that a currency must have some inflation, otherwise people will hoard it and it will not be available for use as a currency.
During the past 500 years, there were long periods of effectively zero inflation where economies boomed. In the industrial revolution in Britain, for example.
Also, I don't think there was such a thing as an economist 500 years ago.
Gold and silver coins kept the price for a pint steady as a rock for hundreds of years.