The Shadow personifies everything that the subject refuses to acknowledge about himself and yet is always thrusting itself upon him directly or indirectly – for instance, inferior traits of character and other incompatible tendencies.
The Shadow is a central concept in Jungian psychology. The human being is born complete, not knowing good and evil. When he begins his process of formation of the Ego – when, in the Garden of Eden, he eats the apple, the fruit of knowledge of good and evil – he becomes potentially able to discriminate between what is good and what is bad. Then, in the process of becoming an adult, in the process of structuring his ego, he chooses certain characteristics that he judges adequate to his personality and represses the ones considered inadequate. Since this is an unconscious process, the individual is not aware of the choices he makes. Features refused are not erased from the psyche, but take refuge in the unconscious, incorporated into what Jung called the Shadow, one of the fundamental archetypes of the human psyche.
We all carry a shadow in our unconscious. In this shadow, we keep the characteristics we neglected in the process of strengthening our ego. Because these characteristics are in the unconscious, we do not recognize them as our own. The problem intensifies because we tend to project these characteristics outside, into other persons.
When we recognize that these characteristics can also be found within our psyche, we get to be more understanding, more conscious.
An example may clarify the subject. I had a niece that was a glutton. As a result, she was too fat. When I saw her eating, I was unusually critical of her, even trying to ridicule her. Years later, after studying Jungian psychology, I understood that her gluttony bothered me above normal levels because I was also a glutton, trying unsuccessfully to lose some weight.
Jung said that knowing your darkness is the best method for dealing with the darkness of other people.
In the Shadow, we keep stored those characteristics that the Ego does not recognize as belonging to the individual. One might think the Shadow to be composed of only bad characteristics, the ugly side of an individual. It is wrong, as the Shadow encompasses all the elements that the Ego considers inappropriate to the image he makes of himself, even those who might be deemed good by a different person. An executive of a company known for his quest for results and the thirst for power, can devalue and suppress good features that are not useful to those who prioritizes the accumulation of material goods, money, power. Compassion, kindness, ability to care for the other are features that can be rejected by his Ego, repressed and sheltered in his Shadow.