When we speak of a thing as being “unconscious” we must not forget that from the point of view of the functioning of the brain a thing may be unconscious to us in two ways—physiologically or psychologically. I shall only deal with the subject from the latter point of view. So that for our purposes we may define the unconscious as “the sum of all those psychological events which are not apperceived, and so are unconscious.”
The unconscious contains all those psychic events which, because of the lack of the necessary intensity of their functioning, are unable to pass the threshold which divides the conscious from the unconscious; so that they remain in effect below the surface of the conscious, and flit by in subliminal phantom forms.
It has been known to psychologists since the time of Leibniz that the elements—that is to say, the ideas and feelings which go to make up the conscious mind, the so-called conscious content—are of a complex nature, and rest upon far simpler and altogether unconscious elements; it is the combination of these which gives the element of consciousness. Leibniz has already mentioned the perceptions insensibles—those vague perceptions which Kant called “shadowy” representations, which could only attain to consciousness in an indirect manner. Later philosophers assigned the first place to the unconscious, as the foundation upon which the conscious was built.
- Paper given before the Section of Neurology and Psychological Medicine, Aberdeen, 1914. Reprinted from the British Medical Journal, by kind permission of the Editor, Dr. Dawson Williams.