In general, his metapsychology represents a technical elaboration of his structural model of the psyche,[3] which divides the organism into three instances: the id is considered the germ from which the ego and the superego emerge.
Driven by an energy that Freud called libido in direct reference to Plato's Eros,[4] the instances complement each other through their specific functions in a similar way to the parts of a microscope or organelles of a cell.
These precise concepts led Freud to say that their unified presentation would make it possible to achieve the highest goal of psychology, namely the development of a comprehensively founded model of health.
Such an idea is crucial for the diagnostic process because illnesses - the treatment and prevention of which is the focus of all medical activity - can only be recognised in contrast to or as deviations from a state of health.
Freud considers findings from these areas of knowledge to be indispensable because without them it is not possible to examine and, where necessary, correct his hypothesis of natural social coexistence in the primordial horde postulated by Darwin (see presented for discussion in Totem and Taboo).
For the same reasons, Freud's claim also extends to the assumed origin of moral codes of behavior (totemism), the differentiation of sexual from social and intellectual needs (instinctively formed communities versus consciously conceived political superstructures; foundations of belief and knowledge systems[8]), and much more.
In a letter dated September 22 of that year he told Fliess: "I am not at all in disagreement with you, not at all inclined to leave psychology hanging in the air without an organic basis.
[15] "When, in his 'Autobiographical Study' of 1925, Freud called his metapsychology a 'speculative superstructure'...the elements of which could be abandoned or changed once proven inadequate, he was, in the terminology of Kant's Critique of Judgment,[16] proposing a psychology als ob or as if – a heuristic model of mental functioning that did not necessarily correspond with external reality.