Specifically, he maintained that the critical agency or the super ego could be accounted for in terms of introjection and that the superego derives from the parents or other figures of authority. The derived behavioural patterns are not necessarily reproductions as they actually are but incorporated or introjected versions of them. Torok and Ferenczi However, the aforementioned description of introjection has been challenged by Maria Torok as she favours using the term as it is employed by Sándor Ferenczi in his essay "The Meaning of Introjection" (1912). In this context, introjection is an extension of autoerotic interests that broadens the ego by a lifting of repression so that it includes external objects in its make-up. Torok defends this meaning in her 1968 essay "The Illness of Mourning and the Fantasy of the Exquisite Corpse", where she argues that Sigmund Freud and Melanie Klein confuse introjection with incorporation and that Ferenczi's definition remains crucial to analysis. She emphasized that in failed mourning "the impotence of the process of introjection (gradual, slow, laborious, mediated, effective)" means that "incorporation is the only choice: fantasmatic, unmediated, instantaneous, magical, sometimes hallucinatory...'crypt' effects (of incorporation)". Fritz and Laura Perls In Gestalt therapy, the concept of "introjection" is not identical with the psychoanalytical concept. Central to Fritz and Laura Perls' modifications was the concept of "dental or oral aggression", when the infant develops teeth and is able to chew. They set "introjection" against "assimilation". In Ego, Hunger and Aggression, Fritz and Laura Perls suggested that when the infant develops teeth, he or she has the capacity to chew, to break apart food, and assimilate it, in contrast to swallowing before; and by analogy to experience, to taste, accept, reject or assimilate. Laura Perls explains: "I think Freud said that development takes place through introjection, but if it remains introjection and goes no further, then it becomes a block; it becomes identification. Introjection is to a great extent unawares." Thus Fritz and Laura Perls made "assimilation", as opposed to "introjection", a focal theme in Gestalt therapy and in their work, and the prime means by which growth occurs in therapy. In contrast to the psychoanalytic stance, in which the "patient" introjects the (presumably more healthy) interpretations of the analyst, in Gestalt therapy the client must "taste" with awareness their experience, and either accept or reject it, but not introject or "swallow whole". Hence, the emphasis is on avoiding