 Freud's clinical methodology at the time, involving the symbolic interpretation of symptoms, the use of suggestion and the exerting of pressure to induce his patients to "reproduce" the deeply repressed memories he posited, has led several Freud scholars and historians of psychology to cast doubt on the validity of his findings, whether of actual infantile abuse, or, as he later decided, unconscious fantasies.Freud did not publish the reasons that led to his abandoning the seduction theory in 1897–1898.For these we have to turn to a letter he wrote to his confidant Wilhelm Fliess dated 21 September 1897.