During the past decades, besides Sigmund Freud, C.G. Jung has been a subject of modern psychobiographical investigations. The revealed documents of Jung and Sabina Speielrein's relationship remarkably changed the narratives of this outstanding story, and it also bears important theoretical consequences. This article focuses on Jung's Siegfried-dream found in his autobiography, since it is closely related to the Freud-Jung-Spielrein triangle, and can be associated with some significant aspects of intellectual history. The text of the dream is treated as an Allportian “first-person document” that can be a starting point of a psychobiographical investigation.