It is a lesson we must not forget. Forecast Spring 2015, European Commission; and “Where are we headed? Perspectives on potential output”, in World Economic Outlook, International Monetary Fund, 2015. 3  Christian Noyer, “Introductory Letter to the Banque de France’s Annual Report”, 4 May 2015.
The statement that "price stability is to be maintained over the medium term" acknowledges the existence of short-term volatility in prices, resulting from non-monetary shocks to the price level such as the effects of indirect tax changes or variations in international commodity prices. There are good economic reasons why monetary policy should be oriented towards the medium term.