ABSTRACT
If the series of 'Papers on Metapsychology' may perhaps be regarded as the most important of all Freud's theoretical writings, there can be no doubt that the present essay on 'The Unconscious' is the culmination of that series. The concept of there being unconscious mental processes is of course one that is fundamental to psycho-analytic theory. The need for postulating any unconscious mental processes was in this way entirely avoided: the chain of physical events was unbroken and complete. In psycho-analysis there is no choice for us but to assert that mental processes are in themselves unconscious, and to liken the perception of them by means of consciousness to the perception of the external world by means of the sense-organs. Co-operation between a preconscious and an unconscious impulse, even when the latter is intensely repressed, may come about if there is a situation in which the unconscious impulse can act in the same sense as one of the dominant trends.
