Taking it in its deepest sense, the shadow is the invisible saurian tail that man still drags behind him. Carefully amputated, it becomes the healing serpent of the mysteries. Only monkeys parade with it. The Integration of the Personality. (1939)
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.
"A Psychological Approach to the Dogma of the Trinity" (1942) In CW 11: Psychology and Religion: West and East. P.286
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.
Aion (1951). CW 9, Part II: P.14
To confront a person with his shadow is to show him his own light. Once one has experienced a few times what it is like to stand judgingly between the opposites, one begins to understand what is meant by the self. Anyone who perceives his shadow and his light simultaneously sees himself from two sides and thus gets in the middle.
"Good and Evil in Analytical Psychology" (1959). In CW 10. Civilization in Transition. P.872
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
There is a deep gulf between what a man is and what he represents, between what he is as an individual and what he is as a collective being. His function is developed at the expense of the individuality. Should he excel, he is merely identical with his collective function; but should he not, then, though he may be highly esteemed as a function in society, his individuality is wholly on the level of his inferior, undeveloped functions, and he is simply a barbarian, while in the former case he has happily deceived himself as to his actual barbarism.Psychological Types (1921). CW 6: P.III
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. "The Philosophical Tree" (1945). In CW 13: Alchemical Studies. P.335
In reality, the acceptance of the shadow-side of human nature verges on the impossible. Consider for a moment what it means to grant the right of existence to what is unreasonable, senseless, and evil! Yet it is just this that the modern man insists upon. He wants to live with every side of himself-to know what he is. That is why he casts history aside. He wants to break with tradition so that he can experiment with his life and determine what value and meaning things have in themselves, apart from traditional resuppositions.
"Psychotherapist for the Clergy" (1932). In CW 11: Psychology and Religion: West and East. P.528