The acquaintance between Sándor Ferenczi and C G Jung pre-dates their first encounter with Sigmund Freud. Later, a triangular relationship developed when the three men crossed the Atlantic together and spent an extended period in one another's company. Ferenczi's friendship with Jung could not survive the latter's break with Freud, but its development between 1907 and 1913 is evidenced by unpublished letters from Jung to Ferenczi, found in the Ferenczi Archive, now at the Freud Museum.