We have long observed that every neurosis has as its result, and probably therefore as its purpose, a forcing of the patient out of real life, an alienating of him from reality. Nor could a fact such as this escape the observation of Pierre Janet; he spoke: of a loss of ‘la fonction du réel’ [‘the function of reality’] as being a special characteristic of neurotics, but without discovering the connection of this disturbance with the fundamental determinants of neurosis. By introducing the process of repression into the genesis of the neuroses we have been able to gain some insight into this connection. Neurotics turn away from reality because they find it unbearable – either the whole or parts of it. The most extreme type of this turning away from reality is shown by certain cases of hallucinatory psychosis which seek to deny the particular event that occasioned the outbreak of their insanity (Griesinger). But in fact every neurotic does the same with some fragment of reality. And we are now confronted with the task of investigating the development of the relation of neurotics and of mankind in general to reality, and in this way of bringing the psychological significance of the real external world into the structure of our theories.
In the psychology which is founded on psycho-analysis we have become accustomed to taking as our starting-point the unconscious mental processes, with the peculiarities of which we have become acquainted through analysis. We consider these to be the older, primary processes, the residues of a phase of development in which they were the only kind of mental process. The governing purpose obeyed by these primary processes is easy to recognize; it is described as the pleasure-unpleasure [Lust-Unlust] principle, or more shortly the pleasure principle. These processes strive towards gaining pleasure; psychical activity draws back from any event which might arouse unpleasure. (Here we have repression.) Our dreams at night and our waking tendency to tear ourselves away from distressing impressions are remnants of the dominance of this principle and proofs of its power.
Sigmund Freud, the Pleasure Principle.