"Well, you split your soul, you see," said Slughorn, "and hide part of it in an object outside the body. Then, even if one's body is attacked or destroyed, one cannot die, for part of the soul remains earthbound and undamaged. But of course, existence in such a form...few would want it, Tom, very few. Death would be preferable."
But Riddle's hunger was now apparent; his expression was greedy, he could no longer hide his longing.
"How do you split your soul?"
"Well," said Slughorn uncomfortably, "you must understand that the soul is supposed to remain intact and whole. Splitting it is an act of violation, it is against nature."
"But how do you do it?"
"By an act of evil—the supreme act of evil. By committing murder. Killing rips the soul apart. The wizard intent upon creating a Horcrux would use the damage to his advantage: He would encase the torn portion—"
—from Chapter 23 of Harry Potter and the Half-Blood Prince, by J.K. Rowling
The impulse to kill another follows directly from a pre-existing act of inner suicide. When we look around us at the principal murderers of our world—George Bush, Osama bin Laden, Dick Cheney, and Tony Blair come to mind—we find that such people act in a preternatural isolation, either on behalf of themselves or their group (a nation or an ideology). The more followers they appear to have, the lonelier and more desolate is their essential condition.
J.K. Rowling reveals Lord Voldemort's absolute isolation repeatedly throughout the Potter series, even as she gives him a cadre of adherents ("death eaters") who display toward him the most superficial and passing loyalty (when Voldemort is powerful and ascendant, they cower before him; but when he appears defeated, they scatter like cockroaches after the bathroom light's turned on).
Voldemort is well aware of the danger occasioned by this interpersonal arrangement: followers who cannot be relied upon to be true in bad times or ambiguous circumstances must be used, and occasionally killed. And when people fail their ruler, or when followers stray from their God, objects must be relied upon as the vessels of power.
Voldemort does this with the horcrux, a magical investment of personal energy into an inanimate object such as a ring, locket, book, or chalice. The object must be precious and unique to the eye of the tyrant who will invest himself in it; in order for there to be power, there must be the image of power in the thing itself. Thus, gods and the other demons of institutional religion are given halos, crowns, and other object-marks of power; a Pope wears sacred robes and a miter; and a President is given a seal of power, a gleaming White House, and $45 million inauguration rituals as his anointment, his horcrux.
But the horcrux metaphor in the Harry Potter story is, I suspect, meant to extend beyond the realms of religious or cultural power. I feel a more immediate and personal meaning in Rowling's symbol of the split personality that has sold its integrity, its natural wholeness, to the images of self defined by a collective ideology. I think that the author is asking each of us to look within ourselves for our own horcruxes, our own acts of inner sacrifice to an object or image of self that has, or is likely to, break us up into disconnected pieces of soul.
I am currently working on a new chapter to my book, The Tao of Hogwarts, that will delve more thoroughly into the metaphor of the horcrux and its potential meaning within our lives. For me, this is another phase in the journey of learning from these remarkable stories that have transfixed readers in every part of the world. My goal, overall, is to help reveal the unique metaphorical values embedded in the Hogwarts tales that have enabled their enduring and seemingly boundless attraction. There are psychological and spiritual lessons contained in these books that most readers can feel but not always articulate for themselves. Thus, in The Tao of Hogwarts, I am simply proposing an opening for an inner dialogue that each reader can take uniquely forward from there into his and her life. To read more excerpts from my book, you can look here or here. As always, I welcome feedback, questions, criticisms, and ideas—just add a comment below.