"There is in enchantment almost always the idea of captivity. Sometimes the stricken victim is literally struck motionless, as when men are turned to stone by the Gorgon,
or the prince of the Arabian Tale is clamped to the earth in marble.
Quite as often the victim of enchantment wanders through the woods as a white hind,
or flies with apparent freedom as a parrot or a wild swan.
But he always talks of his very freedom as a wandering imprisonment. And the reason is that there is always in such witchcraft the note of travesty; the man is disguised and in a double sense 'guyed'; as when the youth in Apuleius feels literally that the witches have made an ass of him.
In contrast with this, it will be noted that the good miracles, the acts of the saints and heroes, are always acts of restoration. They give the victim back his personality; and it is a normal and not a super-normal personality. The miracle gives back his legs to the lame man; but it does not turn him into a large centipede. It gives eyes to the blind; but only a regular and respectable number of eyes. The paralytic is told to stretch forth his hands, which is the gesture of liberation from fetters; but not to spread himself as a sort of Briarean octopus radiating in all directions and losing the human form. There runs through the whole tradition the idea that black magic is that which blots out or disguises the true form of a thing; while white magic, in the good sense, restores to it its own form and not another. St. Nicholas brings two children alive out of a pot when they have already been boiled down into soup; which may be said to mark the extreme assertion of form against formlessness.
But Medea, being a witch, puts an old man into a pot and promises to bring out a young man; that is, another man.
Also Medea, being a witch, does not keep her word."
--from "Magic and Fantasy in Fiction," by G. K. Chesterton.