The term psychic apparatus (also psychical apparatus, mental apparatus) denotes a central, theoretic construct of Freudian

Sigmund Freud

Sigmund Freud , born Sigismund Schlomo Freud , was an Austrian neurologist who founded the discipline of psychoanalysis...

 metapsychology

Metapsychology

Metapsychology is the philosophical study of psychology. Metapsychology, a speculative psychology, is a systematic attempt to discern and describe what lies beyond the facts and laws of psychology, such as the relations between body and mind or concerning the place of the mind in the universe...

, wherein:
As a psychologist

Ego psychology

Ego psychology is a school of psychoanalysis rooted in Sigmund Freud's structural id-ego-superego model of the mind.An individual interacts with the external world as well as responds to internal forces. Many psychoanalysts use a theoretical construct called the ego to explain how that is done...

, Sigmund Freud

Sigmund Freud

Sigmund Freud , born Sigismund Schlomo Freud , was an Austrian neurologist who founded the discipline of psychoanalysis...

 used the German terms psychischer Apparat and seelischer Apparat, about the functioning of which he elaborates:
Freud proposed the psychic apparatus as solely a theoretic construct explaining the functioning of the mind

Mind

The concept of mind is understood in many different ways by many different traditions, ranging from panpsychism and animism to traditional and organized religious views, as well as secular and materialist philosophies. Most agree that minds are constituted by conscious experience and intelligent...

, and not a neurologic

Neurology

Neurology is a medical specialty dealing with disorders of the nervous system. Specifically, it deals with the diagnosis and treatment of all categories of disease involving the central, peripheral, and autonomic nervous systems, including their coverings, blood vessels, and all effector tissue,...

 structure of the brain

Brain

The brain is the center of the nervous system in all vertebrate and most invertebrate animals—only a few primitive invertebrates such as sponges, jellyfish, sea squirts and starfishes do not have one. It is located in the head, usually close to primary sensory apparatus such as vision, hearing,...

:
Moreover, in emphasizing the immateriality of the psychic apparatus, Dr. Freud dismissed the matter of its physical substance: