Freud observes that the invention of the “soul” is an attempt to live forever: we declare an unseen part of ourselves everlasting.

He compares the splitting of the self into some intangible “other” (it is us, but it’s not all of us, but it’s also not fully known to us) as drawing from the tradition of the spirit animal, or the shadow.

The attempt to defy death leads us to partner and externalize a vital component of ourselves.

In Harry Potter the Horcrux Voldemort uses is a soul-fragment reliquary, but its existence outside of his body is a perversion. The soul must remain in the vessel of the body.

Conversely, in His Dark Materials each child has a natural external other, a daemon as embodied reflection or external soul partner.

Leaving fiction, we have the literal and metaphorical shadow, which operates as an alternate self. It is attached but can be relegated to being separate; an oddly unknown dark mirror that is present when we are in the light.

When the shadow self acts we are aghast, as if an external entity has momentarily triumphed and must be relegated outside once again. So, we demote a portion of our soul to live underneath us, behind us, attached to us but ignored so that we maintain interior purity.