[From the letters (to Freud) to the diary (of Ferenczi)].

This article presents the figures of Sigmund Freud and of Sándor Ferenczi as they appear in their exchange of correspondence, in the close interweaving of their private and professional lives. The most critical aspects of the practice of psychoanalysis, which was the passion and constant preoccupation of the two correspondents, are sounded in this correspondence which also shows the relentless effort that was made by the two men to consolidate the theoretical basis of the field. The document that follows this correspondence, Ferenczi's "Clinical diary" thus appears as an act of self-assertion, being addressed to Freud in a manner no longer explicit but implicit.