This apparatus can be set in motion by stimuli, and observation teaches that the stimuli can effect it in three ways: from the outer world through the familiar erogenous zones; from the inner organic world by ways still to be investigated; and from the psychic life, which merely represents a depository of external impressions and a receptacle of inner excitations.
In the case of Gladys, the analyst learned that the all-important stimulus, which Freud referred to, was "from the outer world through the familiar erogenous zones." And he also learned that this stimulus was visual in nature since it consisted of watching her mother engage in anal s*x with a male admirer.
Young Gladys, in her role of voyeur, became sexually excited by watching this first demonstration of overt s*x. And this so
