Psyche (Greek ψυχή breath, blow) was used in classic Greek as a synonym for the word soul. During the course of the centuries since culture (and mind) grew more sophisticated it became necessary to separate the two concepts.
Psyche and soul
Today psyche is one of the four big parts that makes the sum total of the non-physical aspects of a human being; the others are consciousness, mind and soul. Whilst psyche only exists in the body and is connected to the body, soul refers to the part that is unfading.
Functions of psyche
Psyche has two main functions. It is both a non-material „hard disk“ that stores memories as well as a non-material digestion organ that masters fear. Psyche can be of different complexity and can in this respect be compared with a mirror globe that has more or less reflectors on its surface. A globe with less mirrors gives a simple image of reality whilst a globe with many mirrors gives a highly complex image of reality. It is obvious that a highly complexe psyche is able to represent reality more sophisticated but on the other hand is more prone to picture distorted images of reality.
Psyche and health
A strong distortion of reality can lead to a state in which the basic function of psyche temporarily is no longer functioning and fear will no longer be digested correctly. A pathologically working psyche will not only sustain distortions of reality but also intensify them, so that help from outside is necessary (psychoanalysis) to re-enable psyche to sanely digest fear again. As a consequence of this help distortion of reality (which always happens because of fear) can be abolished little by little. Only very seldomly psyche is in rude health which means: A healthy psyche knows the fear but doesn’t allow fear to master it.
Psyche and mind
The word mind relates to the mental abilities of a human, the will, intellect, wit, power of judgement, cogitation separating capability, experiences, education, the ability to discover coherences and the communicative aspects of the human being, like language. Basically mind and psyche work together. Psyche can be accessed by the mind and mind can uncover the distortions of reality that psyche has adapted to.
Psyche and consciousness
Superficially it seems paradoxical that psyche is constructed in a way to primarily store distorted images of reality, but it is only under these conditions that consciousness is needed to develop. Growing consciousness is capable of discovering discrepancies between memories and reality and capable of correcting the distortions of reality with the help of the mind. In this respect psyche is a most precious growth subsidiary for the development of consciousness.
Horizontal and vertical intermediary
By being a non-physical storage organ that is dependent on the supply of the physis (impressions of the world), psyche gives a connective link between the physical (body) and the spiritual aspects (mind, soul) of the human being as well as a bridge between the separated bodies of all the many humans being alive at the same time.
The term „non-material organ“ (copied from the book stated below) is used to relate to these two aspects of psyche: „non-material“ refers to the fact that psyche is not visible whilst „organ“ designates something that inseparably belongs to the body. Hence the non-material quality relativises the idea of an organ inasmuch it is not located in the body, notwithstanding its effects strongly influence the physicalness. – [German version]
Many thanks to the three authors of the book „Welten der Seele“ (Worlds of the soul) that provided these new borderlines between the different parts the human being. This article from G. Axmann mainly is based on these insights: Hasselmann, Varda and Frank Schmolke: Welten der Seele (Worlds of the soul). Munich, 1993. Pages 31-45 (as far as I know only available in German, Italian (Edizioni Mediterranee, Rom) and Portugese (Pensamento, Sao Paulo, Brasilia))