Architectural tropes are commonplace in the tradition of psychological enquiry. Freud himself considers the house an apt image for the human psyche, when he refers to the process of repression and sublimation as an elaborate play of trap doors; in the main, his theory of psychoanalysis is polarized along a vertical axis which stretches from cellar to attic. Not dissimilarly, Jung develops an architectural metaphor when broaching the subject of the collective unconscious: