In Jungian psychology, the shadow or "shadow aspect" may refer to (i) the entirety of the unconscious, i.e., everything of which a person is not fully conscious. (ii) an unconscious aspect of the personality which the conscious ego does not recognize in itself. Because one tends to reject or remain ignorant of the least desirable aspects of ones personality, the shadow is largely negative.
According to Jung, the shadow, in being instinctive and irrational, is prone to projection: turning a personal inferiority into a perceived moral deficiency in someone else. Jung writes that if these projections are unrecognized "The projection-making factor (the Shadow archetype) then has a free hand and can realize its object--if it has one--or bring about some other situation characteristic of its power." These projections insulate and cripple individuals by forming an ever thicker fog of illusion between the ego and the real world.
The shadow may appear in dreams and visions in various forms, and typically 'appears as a person of the same sex as that of the dreamer'. It is possible that it might appear with dark features to a person of any race, since it represents a distant, primitive and indiscriminate aspect of the mind. The shadow's appearance and role depend greatly on the living experience of the individual, because much of the shadow develops in the individual's mind rather than simply being inherited in the collective unconscious. Nevertheless some Jungian maintain that 'The shadow contains, besides the personal shadow, the shadow of society ... fed by the neglected and repressed collective values'.
Jung also made the suggestion of there being more than one layer making up the shadow. The top layers contain the meaningful flow and manifestations of direct personal experiences. These are made unconscious in the individual by such things as the change of attention from one thing to another, simple forgetfulness, or a repression. Underneath these idiosyncratic layers, however, are the archetypes which form the psychic contents of all human experiences. Jung described this deeper layer as "a psychic activity which goes on independently of the conscious mind and is not dependent even on the upper layers of the unconscious—untouched, and perhaps untouchable—by personal experience" (Campbell, 1971). This bottom layer of the shadow is also what Jung referred to as the collective unconscious.