In an historical context focused on a close examination of the complex relationship between Freud and Ferenczi, the author shows Ferenczi's contribution to the evolution of psychoanalysis. He describes how his ideas and his therapeutic sensitivity anticipated modern clinical thought (for example, Winnicott and Bion), especially the understanding of borderline and narcissistic pathology. The paper considers the following topics: transference and countertransference; early affectivity; the different psychic trauma; phenomena connected with dissociation; the healing factor of the analysis.