The volume, Hermann Hesse Briefwechsel mit seinem Psychoanalytiker Josef Bernhard Lang, sheds light on the medical, friendly and artistic relationship between the psychoanalyst Josef Bernhard Lang and his writer-patient, Hermann Hesse. It offers the literary and psychoanalytical world a singular and little-known portrait of Dr. Lang, a discreet man in perpetual search of truth and knowledge, who was a great source of inspiration and adaptation for Hesse's work. In the person of Lang, Hesse discovered psychoanalytic treatment, Gnostic doctrine and also watercolor painting. From an initially strictly medical correspondence that allowed the patient to arrange appointments with his psychoanalyst, the relationship developed into a long friendship between the two men who shared a sense of complicity and a common interest in German literature, philosophical reflection, the arts and music. This correspondence is also a rich testimony to the interdisciplinary links and dynamics between psychoanalysis and literature.