A detailed study is made of the paper Strachey presented at the British Society in 1933 and of his exposition at the Marienbad Congress, pointing out the similarities and the differences between them which mark an evolution in the outlook of this great English analyst.

The influence on Strachey of 'Group Psychology and the Analysis of the Ego' and of the Salzburg Congress is easily recognizable, but what distinguishes his contribution is to have separated, with great theoretical precision, the fundamental instrument of analysis—interpretation—from suggestion. By defining the conditions in which the mutative effect takes place, while at the same time giving the reasons that make transferential interpretation the only field of this action, Strachey makes a lasting contribution to psychoanalysis and lays the foundations which, with the development of our knowledge, have made insight stand today at the centre of the most convincing explanations on the nature of psychoanalysis' therapeutic action.