From C.G. Jung,
Aion: Researches into the Phenomenology of the Self, trans. R.F.C. Hull (London, 1959), pp. 8-9:
II
THE SHADOW
Whereas the contents of the personal unconscious are acquired during the individual's lifetime, the contents of the collective unconscious are invariably archetypes that were present from the beginning. Their relation to the instincts has been discussed elsewhere. The archetypes most clearly characterized from the empirical point of view are those which are those which have the most frequent and most disturbing influence on the ego. These are the
shadow, the
anima, and the
animus. The most accessible of these, and the easiest to experience, is the shadow, for its nature can in large measure be inferred from the contents of the personal unconscious. The only exceptions to this rule are those rather rare cases where the positive qualities of the personality are repressed, and the ego in consequence plays an essentially negative or unfavourable role.
The shadow is a moral problem that challenges the whole ego-personality, for no one can become conscious of the shadow without considerable moral effort. To become conscious of it involves recognizing the dark aspects of the personality as present and real. This act is the essential condition for any kind of self-knowledge, and it therefore, as a rule, meets with considerable resistance. Indeed, self-knowledge as a psychotherapeutic measure frequently requires much painstaking work extending over a long period.
Closer examination of the dark characteristics - that is, the inferiorities constituting the shadow - reveals that they have an
emotional nature, a kind of autonomy, and accordingly an obsessive or, better, possessive quality. Emotion, incidentally, is not an activity of the individual but something that happens to him. Affects occur usually where adaptation is weakest, and at the same time they reveal the reason for its weakness, namely a certain degree of inferiority and the existence of a lower level of personality. On this lower level with its uncontrolled or scarcely controlled emotions one behaves more or less like a primitive, who is not only the passive victim of his affects but also singularly incapable of moral judgement.
Although, with insight and good will, the shadow can to some extent be assimilated into the conscious personality, experience shows that there are certain features which offer the most obstinate resistance to moral control and prove almost impossible to influence. These resistances are usually bound up with
projections, which are not recognized as such, and their recognition is a moral achievement beyond the ordinary. While some traits peculiar to the shadow can be recognized without too much difficulty as one's own personal qualities, in this case both insight and good will are unavailing because the cause of the emotion appears to lie, beyond all possibility of doubt, in the
other person. No matter how obvious it may be to the neutral observer that it is a matter of projections, there is little hope that the subject will perceive this himself. He must be convinced that he throws a very long shadow before he is willing to withdraw his emotionally-toned projections from their object.