Death
Death is the end of a living organism's life, technically defined in humans as either the permanent termination of heart function and respiration, or of brain activity.
- Page adapted from Death
at the Harry Potter Lexicon.
Afterlife
While Death is understood in a purely physical sense, the nature of what lies beyond it is a mystery to wizards and witches and Muggles alike. When a wizard or witch dies, unlike a Muggle, he or she can choose to leave behind an imprint of their soul in the mortal world in the form of a ghost. Few opt to become ghosts, however, as it means they will never "go on" like most people do. Those who cross over to the other side cannot come back in any form resembling the physical body they had in life. The exception being the beings brought back using the Resurrection Stone. However, it is described that they do not belong in the mortal world, being only a semi-corporeal form, "less substantial" than a living body but "much more" than a ghost.
Immortality and Resurrection
There is no known way to magically reunite a person's soul with their body once they have died. Many young witches and wizards discovered this through the story of Babbitty Rabbitty and Her Cackling Stump (in which the protagonist Babbitty is blackmailed by a charlatan to perform magic for a king, but doesn't bother raising her wand when the king attempts to raise a dog from the dead.) During the six centuries have elapsed since Beedle wrote the tale, innumberable ways have been devised to maintain the illusion of the continuing presence of one's loved ones. For example, wizarding photographs and portraits move and (in the case of the latter) talk just like their subjects.
Similarly, the Mirror of Erised may also reveal more than a static image of a lost loved one. Ghosts are transparent, moving, talking, and thinking versions of wizards and witches who decided, for whatever reason, to remain on earth. The closest to resurrecting the dead would be the Resurrection Stone, which can recall someone who has died from the beyond, but they will return only in a semi-corporeal form, "less substantial" than a living body but "much more" than a ghost, but which if it ever truly existed has been lost.
- —Bertrand de Pensées-Profondes in A Study into the Possibility of Reversing the Actual and Metaphysical Effects of Natural Death, with Particular Regard to the Reintegration of Essence and Matter'
Despite this, wizards have still not found a way of reuniting body and soul once death has occurred. This subject was covered by eminent Wizarding philosopher Bertrand de Pensées-Profondes in his celebrated work A Study into the Possibility of Reversing the Actual and Metaphysical Effects of Natural Death, with Particular Regard to the Reintergration of Essence and Matter, during which he stated that reversing death would never be physically possible. Phoenixes are the sole exception to the rules of death, as they can be reborn from their ashes without any restraints or assistance.
However, while there exists no known method of reversing death once it has occurred, there are certain things a witch or wizard can do to postpone their death or prolong their life (even further than the longevity which would seem to be granted by magical ability).
The Elixir of Life, which is made from the Philosopher's Stone, will grant a person extended life for as long as they continue to consume it. However, because the only known Philosopher's Stone was destroyed in 1992, this method is no longer available.Unicorn blood can keep alive a person who is near death, but unicorns are such pure, defenceless creatures that a person who kills one and drinks its blood will have "but a half-life." A wizard or witch who rips their soul through an act of murder can place that torn fragment inside of an external object called a Horcrux.
By binding a part of their soul to the earth, the Horcrux prevents the wizard or witch from dying, even if their body is injured or completely destroyed. There is a potion which enables the Horcrux-creator's body to be reconstructed in the latter scenario. Overall, however, many wizards and witches would prefer death over such a pitiful state of existence.
Corpses can also be reanimated through Dark magic. Known as Inferi, these creatures are not alive, and simply do whatever the wizard who controls them wants, like puppets.
Study and perception of death
There is a chamber in the Department of Mysteries where witches and wizards study the mysteries of death. In this chamber is the Veil, an ancient stone archway, which is a gateway between the world of the living and the world of the dead. People standing around the Veil may hear voices from the other side depending on their level of faith in an afterlife. Passing through the veil causes immediate death.
Although many fear death due to the unknown that lies beyond life, few would ever choose to manipulate and damage their own souls to remain behind in a pitiful existence. Horcruxes and remaining as ghosts are two known methods of immortalizing one's existence in the plane of living, but the former has dire consequences that few would ever want it, while the latter means entrapment for eternity that only those who fear or have deep bonds would choose it.
Thestrals are magical creatures visible only to people who have witnessed a death firsthand. However, the ability to see thestrals does not come immediately, but only after one has had time to fully understand death and its finality.
