It has tested the armoury of instruments available to central banks and the limits of their policy force. It has also reopened questions that we thought had been answered and renewed debates that we thought had been settled. My own experience has been that real world problems are too complex to fit template solution of text books.
Last, but by no means least, the NCBs play an indispensable role in communications. Undoubtedly, the multinational, multi-lingual set-up of the Eurosystem presents a challenge, to say the least.