[adapted from http://www.jungcircle.com/muse/shadow.html]
1. Unfortunately there can be no doubt that man is, on the whole, less good than he imagines himself or wants to be. Everyone carries a shadow, and the less it is embodied in the individual's conscious life, the blacker and denser it is. If an inferiority is conscious, one always has a chance to correct it. Furthermore, it is constantly in contact with other interests, so that it is continually subjected to modifications. But if it is repressed and isolated from consciousness, it never gets corrected.
"Psychology and Religion" (1938). In CW 11: Psychology and Religion: West and East. P.131
2. It is a frightening thought that man also has a shadow side to him, consisting not just of little weaknesses- and foibles, but of a positively demonic dynamism. The individual seldom knows anything of this; to him, as an individual, it is incredible that he should ever in any circumstances go beyond himself. But let these harmless creatures form a mass, and there emerges a raging monster; and each individual is only one tiny cell in the monster's body, so that for better or worse he must accompany it on its bloody rampages and even assist it to the utmost. Having a dark suspicion of these grim possibilities, man turns a blind eye to the shadow-side of human nature. Blindly he strives against the salutary dogma of original sin, which is yet so prodigiously true. Yes, he even hesitates to admit the conflict of which he is so painfully aware.
"On the Psychology of the Unconscious" (1912). In CW 7: Two Essays on Analytical Psychology. P.35
3. We know that the wildest and most moving dramas are played not in the theatre but in the hearts of ordinary men and women who pass by without exciting attention, and who betray to the world nothing of the conflicts that rage within them except possibly by a nervous breakdown. What is so difficult for the layman to grasp is the fact that in most cases the patients themselves have no suspicion whatever of the internecine war raging in their unconscious. If we remember that there are many people who understand nothing at all about themselves, we shall be less surprised at the realization that there are also people who are utterly unaware of their actual conflicts.
"New Paths in Psychology" (1912). In CW 7: Two Essays on Analytical Psychology. P.425
4. If you imagine someone who is brave enough to withdraw all his projections, then you get an individual who is conscious of a pretty thick shadow. Such a man has saddled himself with new problems and conflicts. He has become a serious problem to himself, as he is now unable to say that they do this or that, they are wrong, and they must be fought against. He lives in the "House of the Gathering." Such a man knows that whatever is wrong in the world is in himself, and if he only learns to deal with his own shadow he has done something real for the world. He has succeeded in shouldering at least an infinitesimal part of the gigantic, unsolved social problems of our day.
"Psychology and Religion" (1938). In CW 11: Psychology and Religion: West and East. P.140
5. We carry our past with us, to wit, the primitive and inferior man with his desires and emotions, and it is only with an enormous effort that we can detach ourselves from this burden. If it comes to a neurosis, we invariably have to deal with a considerably intensified shadow. And if such a person wants to be cured it is necessary to find a way in which his conscious personality and his shadow can live together.
"Answer to Job" (1952). In CW 11: Psychology and Religion: West and East. P.12
6. When we must deal with problems, we instinctively resist trying the way that leads through obscurity and darkness. We wish to hear only of unequivocal results, and completely forget that these results can only be brought about when we have ventured into and emerged again from the darkness. But to penetrate the darkness we must summon all the powers of enlightenment that consciousness can offer.
"The Stages of Life" (1930). In CW 8: The Structure and Dynamics of the Psyche. P.752
7. The hero's main feat is to overcome the monster of darkness: it is the long-hoped-for and expected triumph of consciousness over the unconscious. The coming of consciousness was probably the most tremendous experience of primeval times, for with it a world came into being whose existence no one had suspected before. "And God said, 'Let there be light"' is the projection of that immemorial experience of the separation of consciousness from the unconscious.
"The Psychology of the Child Archetype" (1940). In CW 9, Part I: The Archetypes and the Collective Unconscious. P.284
8. Just as we tend to assume that the world is as we see it, we naively suppose that people are as we imagine them to be. In this latter case, unfortunately, there is no scientific test that would prove the discrepancy between perception and reality. Although the possibility of gross deception is infinitely greater here than in our perception of the physical world, we still go on naively projecting our own psychology into our fellow human beings. In this way everyone creates for himself a series of more or less imaginary relationships based essentially on projection.
"General Aspects of Dream Psychology" (1916). In CW 8: The Structure and Dynamics of the Psyche. P.507
9. The change of character brought about by the uprush of collective forces is amazing. A gentle and reasonable being can be transformed into a maniac or a savage beast. One is always inclined to lay the blame on external circumstances, but nothing could explode in us if it had not been there. As a matter of fact, we are constantly living on the edge of a volcano, and there is, so far as we know, no way of protecting ourselves from a possible outburst that will destroy everybody within reach. It is certainly a good thing to preach reason and common sense, but what if you have a lunatic asylum for an audience or a crowd in a collective frenzy? There is not much difference between them because the madman and the mob are both moved by impersonal, overwhelming forces.
"Psychology and Religion" (1938). In CW 11: Psychology and Religion: West and East. P.25
10. 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.
11. Filling the conscious mind with ideal conceptions is a characteristic of Western theosophy, but not the confrontation with the shadow and the world of darkness. One does not become enlightened by imagining figures of light, but by making the darkness conscious.
12. Projections change the world into the replica of one's own unknown face.
13. Good does not become better by being exaggerated, but worse, and a small evil becomes a big one through being disregarded and repressed. The shadow is very much a part of human nature, and it is only at night that no shadows exist.