Sorcery

[radagastly]

Cambridge Dictionaries Online defines sorcery as:

a type of magic in which spirits (= beings that cannot be seen), especially evil ones, are used to make things happen

If that is specifically what you are referring to, then the Barrow-Wight, (not our own esteemed Barrow Wight, but the Ghost Prince of Cardolan), was a victim of sorcery. He was raised (or actually re-raised) from the dead by the Witch-King to keep an "eye" on the Barrow Downs knowing that the Ring, and therefore, its bearer, would be passing eastward toward either Elrond or Galadriel for advice and that they might have to pass through the 'Downs to get there. (I've always felt that was the reason Tom Bombadil kept the Hobbits at his house for an extra day, because the Witch King was wandering the 'Downs and the Old Forest while they were there, but that's another thread.)

Clearly, Aragorn used the same kind of power to bring the Dead with him from the Paths of the Dead. In Middle Earth, magic of all kinds is neutral, but the motive on how it is used defines whether it is Good or Evil.

Tolkien was a Catholic, and I was raised as such. As a student of Mythology and Religion (inextricable from word-history), Tolkien would have been aware of those religions (such as Voudon [Voodoo] and Santaria, to name a couple], that pray to the Saints for some kind of intervention, but would also have known that praying to the Catholic Saints for their intervention was really no different, except for the motives of the individuals doing the asking. Good and Evil lie in the human heart, not in the means uesd to achieve their particular end. There is at least as much "positive" motive behind Voodoo as there is 'negative.' It's not all about just sacrificing chickens and goats.

In The Hobbit , Tolkien names Sauron "The Necromancer," another name for a sorcerer. A necromancer raises the Dead. Appropriate, considering he was probably reviving the Nazgul at the time. They weren't dead, but they were certainly no longer alive. Who else might he have been raising from the Dead? Or was Sorcery just a "Front" to make him look more human (Numenorian)? He fled as soon as he was discovered. What does it take to persuade someone away from the Halls of Mandos? And how do you effect their escape? And, what if they are human and have already departed the Circles of the World? How do you get them back?

It's a tricksy sort of magic, this Sorcery. The other kind taps into the power of Middle Earth itself, much easier. Nearly as easy as performing magic here, in the real world.