Faust shows with great power that the redemption of the ego is possible only as the redemption of the shadow parallels it. As the shadow is drawn up into consciousness, it becomes softer, more pliable, more gentle. Faust's character is filled out by the addition of his shadow. He is made whole by his encounter with Mephistopheles, and the same is true in reverse. Better said, neither ego nor shadow can be redeemed unless its twin is transformed.
It is this rubbing together that brings them back to their original wholeness. This is nothing less than healing the split between heaven and hell. Lucifer (another name for our shadow) was once part of the heavenly host, and he must be restored to his rightful place by the end of time. This vast mythological statement applies to the individual psyche as well: it tells us that it is the task of every man and woman to restore the shadow and redeem our rejected qualities.