Psychological discoveries of a certain kind give rise to a particular sense of shock. When we are forced to look afresh at something whose importance we think we already know, we may find it has new and unexpected significance. Our previous understanding, genuine as it was, comes to seem rather shallow.

Psychoanalysts must be open to such experiences, and I illustrate this with episodes from the history of psychoanalysis and with clinical examples. 'What really matters about this analysis?' is a question for which patient and analyst must each seek an answer, and both must allow it to take them by surprise. There is a parallel between the patient's need to give up his established ways of coping and the analyst's need not to cling on to his familiar ways of understanding.