"This onslaught came down upon us as a bolt from the blue. Its effect on Bohr was remarkable... as soon as Bohr had heard my report of Einstein’s argument, everything else was abandoned: we have to clear up such a misunderstanding at once. We should reply by taking up the same example and showing the right way to speak about it. In great excitement, Bohr immediately started dictating to me the outline of such a reply. Very soon, however, he became hesitant. ‘No, this won’t do, we must try all over again... we must make it quite clear...’ So it went on for a while, with growing wonder at the unexpected subtlety of the argument."