What is 'Dark Magic'?

[mongo62aa]

No: HPFGUIDX 95534

What exactly is 'Dark Magic'?  This has never been answered in 
canon.  Many fans assume that the difference between 'Dark Magic' 
and 'Light Magic' has to do with the intended results, but this 
cannot be right, as many 'Light Magic' spells can be used to hurt or 
kill others--for example, the Reducto Curse, which Harry uses in the 
Third Task to blow a hole in a hedge, would also blow a person 
apart.  The three 'Unforgivable Curses' may, if used, be cause to be 
sent to Azkaban, but they are not specifically named as 'Dark Magic'.
 
Another theory is that 'Dark Magic' has to do with controlling 
spirits or demons, in the same manner as the classical concept of 
sorcery or necromancy.  This is possible, but there is no evidence 
that I am aware of that such a thing exists in the Potterverse.
 
I have recently come across an explanation of 'Dark Magic', as well 
as 'Ancient Magic', that makes a lot of sense to me as being 
historically plausible within the Potterverse.  It is described in 
one of a large collection of interconnected essays on a possible 
(and quite plausible, in my opinion) history of the Potterverse.  
The collection can be found at:
 
http://www.redhen-publications.com/Potterverse.html
 
and the essay in question can be found at:

http://www.redhen-publications.com/HistoryofMagic.html
 
I will present a compressed and simplified version of the essay here.

According to this history, humans are not designed to handle magic, 
unlike various 'magical' plants and animals. In much the same way as 
certain animals have evolved to use electricity as a weapon, or have 
developed an extra sense that can directly perceive electricity, so 
have certain plants and animals evolved to directly use magic.
 
Humans, however, have not.  The emergence of certain genes to allow 
the use of magic is comparatively recent in humans, and their bodies 
have not yet developed to the point where the direct use of magic is 
safe.  The first encounters with magic would have been in the form 
of 'Wild Magic', which must have had much the same result as 
encountering electricity in the form of 'Lightning'.  Few people 
could have survived the experience.  For a long time, efforts must 
have been made to learn to at least partially control this 'Wild 
Magic', with the aim of being able to use it and survive the 
experience.  The early shamans would have used a variety of 
techniques, including meditation and mind-altering drugs, along with 
(eventually) artifacts such as staffs, to make an encounter with 
Magic less lethal, but they must still have actually used Magic only 
very rarely.  They may have performed a 'Great Magic' a handful of 
times in their entire life--it would have been too dangerous to do 
it more often.  Many of the wide variety of techniques that were 
invented at this early time would be still known, under the umbrella 
term of 'Ancient Magic'--very dangerous, but very powerful.
 
The big breakthrough in magical technology is without a doubt the 
wand--a stick of wood with a magically reactive core.  At a stroke, 
this would have made the practice of magic much safer, as the 
magical energies would no longer pass through the human body (which 
is not designed to handle these energies) but instead through the 
wand (which is designed to do so).  Once a witch or wizard had a 
wand, they could perform a vastly greater amount of magic without 
fear of physical injury or destruction.  However, after a few years 
or decades, another problem emerged.  People who had performed a lot 
of magic with their wand were going insane.  Eventually, it became 
clear that the use of magic with a wand has a degenerative effect on 
the caster's mind and spirit, so that their 'humanity' was gradually 
stripped away.  The problem lay in the fact that, although the 
magical energies were safely conducted through their wands, the 
magic was still controlled directly through the spirit or soul.  
Magic, like electricity or water, always seeks the shortest path 
to 'ground', and constant passage through the caster's soul tends to 
erode the soul's configuration to allow for this effect.  As time 
goes on, and the caster's soul grows more eroded and less human, the 
magic flow increases, making them more powerful, but also less sane.
 
A solution to this problem finally emerged with the discovery 
of 'Light Magic'.  This is magic controlled by such things as spoken 
incantations and wand movements, rather than directly through the 
spirit.  By definition, if indirectly-controlled magic is 'Light', 
then all the old magic is 'Dark'--whatever its intended purpose.  
Good or evil has nothing to do with it.  'Light Magic' was much less 
perilous than the older forms, because the soul was not eroded by 
its use.  Much of the magical research of the time must have been to 
find ways to duplicate the powers of 'Dark Magic' using 'Light 
Magic'.  A problem would have emerged, though: because the control 
of the magic flow in 'Light Magic' is indirect, and also cannot 
increase as the soul erodes, the magic would have been less powerful 
than 'Dark Magic' can provide.  Hence some people would continue to 
use 'Dark Magic', even knowing its ultimate price.  Since these 
people are the ones who are less caring about others to begin with, 
and because they would eventually go mad and become dangerous, 'Dark 
Magic' eventually acquired a reputation as being evil.
 
This explanation makes a lot of sense to me.  It is probably not 
what JKR had in mind--if she thought about it at all--but, combined 
with the other essays in the collection, we have a believable, 
plausible explanation of how the Potterverse came to be.  Two other 
core essays in the collection are:
 
http://www.redhen-publications.com/Magic&Wizards.html
 
http://www.redhen-publications.com/Wizards&Muggles.html
 
These three essays, together, provide a very believable outline of 
the history of the Potterverse, which the rest of the essays fill in.
 
Bill