Magic"Any sufficiently advanced technology is indistinguishable from magic."
That quote from Arthur C. Clarke is probably as good a place to begin this discussion as any. What is magic? As with the question "what is reality," the answer is multiple choice:
It's probably best to break the topic down into bite-sized chunks.
Manipulating NatureThe original and still best use of magic is as a tool to get what you want. Easy enough, but there are a variety of techniques, all of which have a few common denominators. First, the practitioners of each tend to hate each other. Second, none of them perform extremely well in controlled settings such as scientific laboratories.
The major schools of magic are:
Religion and MagicNo matter how much they would prefer to deny it, all Religion has an element of magic to it, whether it's Christianity, Islam, Judaism or Buddhism.
Religious magic comes in a number of flavors, the most common of which involves invoking the name of a supernatural entity and petitioning said entity for favors, usually in a very stylized format. Widely referred to as "praying," this has long been considered one of the most ineffective forms of magic.
Some religions have specific schools of magic. Judaism has the kabbalah, Islam has Sufism. Buddhism is associated with a variety of magical and healing practices, based on regional traditions.
Christianity also has magic, but they get really pissed off when you call it that. Roman Catholicism has the most developed magical rituals, with novenas (ritual magic designed to manipulate reality), Relics and Talismans aplenty, and secret(ish) rituals like Exorcism.
But Protestants have their fair share of magical practices as well, many centers around invoking the name of Jesus Christ. Other Protestant practices include ritual possession (speaking in tongues) that is very similar to Voudoun and Faith Healing, a staple of Televangelists.
Magic and SatanDespite the fact that all religions include magic (see above), many of these same religions thoroughly denounce magic as the work of Satan and insist that any effort to cause other-than-natural alterations to one's environment.
While some magic practices are based around this concept, the vast majority of currently surviving types of magic tend to eschew the whole idea of Satan as an oppressive tool of the reigning authority structure.
You will find extraordinarily few individuals who will cop to the fact that they actually invoke Satan or anyone resembling him, but they are out there if you're sufficiently motivated to find them.
There are, however, a number of magic schools which involve the worship and/or befriending of non-Christian deities (such as Odin, "the Goddess," Isis or Shiva) which in the minds of many Christians automatically qualifies as Satanism.
Magic for the MassesWhether as a sincere effort or a deliberate fraud, one of the most effective ways to control people is to convince them you have magical powers, the effects of which they are subject to, but the secrets of which they have been denied.
This involves pretty much the same dynamic as duping people on the basis of religious authority. First, you convince them to believe the general principle, then you convince them that you (and only you) are the one true incarnation of that principle.
First you convince people they have seen something unexplainable. You're halfway there. Once their sense of reality has been shaken, all you have to do for a follow-up is present an explanation they can accept. It helps if you can repeat the initial unexplainable thing at will.
Stage MagicStage magic is a weird outgrowth of traditional magic, in much the same way that Professional Wrestling is a weird outgrowth of traditional wrestling. Stage magic is almost always performed by a male, and usually a flamboyant and irritating male who would not be welcome in your home for dinner.
In stage magic, the magician gets up before an audience and performs seemingly impossible stunts like mind reading, sawing a woman in half or making the Statue of Liberty disappear.
Despite the often very impressive nature of these feats, the stage magician does not attempt to present himself as a spiritual leader, instead offering up his miracles with a wink-wink admission that it's a trick and daring the viewer to try to figure it out.
Although entirely innocuous (and usually vacuous), stage magic is nevertheless condemned by several stripes of fundamentalists as somehow glorifying Satanism or Witchcraft. These charges usually come from people who would be a lot better off getting a life.
Unexplained PhenomenaHere's the funny thing. Science has generally been unable to measure, replicate or prove the vast majority of claims relating to magical power (with the exception of some healing practices, which do have some measurable benefits). But the underlying principles behind magic haves actually gained ground over the last 100 years, as science unfolds the secrets of time, quantum physics and chaos theory.
Consider just a few choice examples:
Generally speaking, the scientific breakthroughs of the last several decades have cast serious doubt on specific practitioners of magic while at the same time strengthening magic's underlying concepts. Any sufficiently advanced technology could end up making ancient ideas a firmly accepted consensus reality.
What this boils down to is a fairly familiar story in the history of the human race: A bunch of people had generally the right idea but managed to fuck up the execution.
Of course, you can apply that statement to just about every human endeavor, whether it be magic, democracy, atomic power, medicine, sex, religion, the 1960s, relationships, television, or traffic laws. As above, so below...