The author demonstrates with clinical material that mirror dreams occur as a rule at a time of crisis when an emerging wish, or a forbidden success related to Oedipal conflicts centering around primal scene fantasies, may cause the superego to threaten the self with castration. The mirror dream represents a defense against this threat. According to the author it accomplishes this by a process which involves a reversal of superego formations. The threatening introject is projected onto the mirror and is reintrojected as a protector of narcissism, after having been magically mastered by omnipotent voyeurism. Thus, when threatened, narcissistic mortification disturbs the dreamer's sleep, the dreamer looks into the mirror as a wakened sleeper might inspect his room for a source of