Regarding this, Freud stated: We assume that mental life is the function of an apparatus to which we ascribe the characteristics of being extended in space and of being made up of several portions [Id, ego and super-ego].As a psychologist, Sigmund Freud used the German terms psychischer Apparat and seelischer Apparat, about the functioning of which he elaborates: We picture the unknown apparatus, which serves the activities of the mind, as being really like an instrument constructed of several parts (which we speak of as 'agencies'), each of which performs a particular function, and which have a fixed, spatial relation to one another: it being understood that by 'spatial relation'—'in front of' and 'behind', 'superficial' and 'deep'—we merely mean, in the first instance, a representation of the regular succession of the functions.Freud proposed the psychic apparatus as solely a theoretic construct explaining the functioning of the mind, and not a neurologic structure of the brain.
'Open to revision', we can say in such cases ... the value of a 'fiction' of this kind ... depends on how much one can achieve with its help.Freud's model was not concerned with describing psychic life in terms of physical substance: That is not a subject of psychological interest.
[6] Though seemingly related, it was never specified by Freud whether the introduction of the Id, ego, and superego was intended to replace or expand the psychoanalytic model of the psychic apparatus.
It has been theorized that it may have been a temporary placeholder prior to the conception and public introduction of ideas such as the id, ego, and superego, making it a foundation upon which Freud could further his expansion of a physiological and mental correspondence in relation to human functioning.
[7][8] However, the most commonly held belief within the psychoanalytic community is that the model of the psychic apparatus was intended by Freud to be the "whole" in which many parts- such as the id, ego, and superego- function throughout,[9] in search of pleasure and avoidance of pain.