A patient's fantasy that his body becomes rigid and immobile while he is looking at his mother's nude body and genitalia made Coriat reconsider the problems of the symbolism of Medusa's head. He confirms Freud's and Ferenczi's interpretations according to which the Medusa represents the terrifying sight of the female (maternal) genitalia which are perceived as 'castrated'. Coriat emphasizes the unauthorized onlooker's punishment: petrifaction. The metamorphosis into stone certainly symbolizes an erection (according to the symbolic equation: body = phallus); but through the immobility it simultaneously symbolizes 'the impotence of fear, a protection against incest, a form of punishment for forbidden incestuous wishes'.