The basic principle of structural analysis, I was explaining, is that the terms of a symbolic system do not stand in isolation—they are not to be thought of in terms of what they 'stand for,' but are defined by their relations to each other. One has to first define the field and then look for elements in that field that are systematic inversions of each other. Take vampires. First you place them: vampires are stock figures in American horror movies. American horror movies constitute a kind of cosmology, a universe unto themselves. Then you ask: what, within this cosmos, is the opposite of a vampire? The answer is obvious. The opposite of a vampire is a werewolf. On one level they are the same: they are both monsters that can bite you and, biting you, turn you, too, into one of their own kind. In most other ways each is an exact inversion of the other. Vampires are rich. They are typically aristocrats. Werewolves are always poor. Vampires are fixed in space: they have castles or crypts that they have to retreat to during the daytime; werewolves are usually homeless derelicts, travelers, or otherwise on the run. Vampires control other creatures (bats, wolves, humans that they hypnotize or render thralls). Werewolves can't control themselves. Yet—and this is really the clincher in this case—each can be destroyed only by its own negation: vampires, by a stake, a simple sharpened stick that peasants use to construct fences; werewolves, by a silver bullet, something literally made from money.
David Graeber