The sense of guilt, the severity of the super-ego, is therefore the same thing as the rigour of conscience; it is the perception the ego has that it is watched in this way, the ego’s appreciation of the tension between its strivings and the standards of the super-ego
Freud identifies the sense of guilt structurally with superego severity and the ego’s masochistic submission to an inner critical agency, grounding guilt in the psychic economy of civilization itself.
, Civilization and Its Discontents, 1930thesis