The persona is the socially acceptable part of ourselves. It's the mask that we choose to show others in order to fit in, be accepted and be successful in the world. It's like a store front where we display our best products in the best light possible.
But according to the late psychiatrist Carl Jung, everyone has another side of themselves called the shadow self, or the dark side. The shadow is that part of ourselves that we not only hide from others, but also from ourselves.
It's the part of ourselves that we have judged to be negative, unacceptable, and unworthy and thus we have denied, rejected, condemned and repressed.
The shadow not only contains negative aspects such as unhealed wounds, addictions, shame, sadness and other emotional trauma, but also positive aspects as well.
If we are very creative and imaginative, but as children we were often discouraged from expressing our creativity because we were raised up in an environment that was very practical and realistic, we might have tried to repress our creativity and it would then become part of the shadow.
"The shadow, when it is realized, is the source of renewal; the new and productive impulse cannot come from established values of the ego. When there is an impasse, and sterile time in our lives—despite an adequate ego development—we must look to the dark, hitherto unacceptable side which has been at our conscious disposal." -Edward Whitmont
Deep within the dark caverns of our subconscious mind holds not only features of our psyche that are destructive, but it also contains powerful creative urges and other hidden abilities.
It was Joseph Campbell who said that "the cave you fear to enter holds the treasure that you seek." The shadow holds hidden reservoirs of regeneration and renewal, and healing the dark side can be a catalyst for a spiritual rebirth.