Between 1920 and 1925 a shift occurred in psychoanalytic theory that related primarily to the status of aggression. The author shows which authors in Berlin, Amsterdam and London participated in this change and to what extent they prepared the ground for the reception of Melanie Klein, who developed in her analyses of children a technique that applied pre-eminently to the perception and interpretation of aggression. The way in which Freud distanced himself from this departure from the primacy of the sexual is described, as well as the waning importance of his perspective following the establishment of the Institutes in Berlin and London.