the most complete and the simplest illustration of this is perhaps the series of pictures contained in the Rosarium philosophorum of 1550… Its psychological importance justifies closer examination. Everything that the doctor discovers and experiences when analysing the unconscious of his patient coincides in the most remarkable way with the content of these pictures.
Jung identifies the Rosarium philosophorum picture-series as the primary alchemical document for understanding the psychology of the transference, asserting its direct correspondence with clinical analytic experience.
, The Practice of Psychotherapy: Essays on the Psychology of the Transference and Other Subjects, 1954thesis