The word comes from a Latin verb meaning to bristle. Horror is first of all a bodily event: the hair rising on the neck, the skin tightening, the breath held. It is one of the least pleasant sensations a person can have, and a large part of the world's entertainment industry exists to supply it.
This is a genuine puzzle, and an old one. We would run from a real corpse in the cellar, and we will pay to watch a fictional one climb the stairs. A person who would be traumatized by a single night in a haunted house will read a novel about one in bed, alone, with the lamp turned down for effect. This essay sets out the main answers that have been given to the puzzle. None is complete. Together they say a good deal about what fear is for.
The safe distance
The oldest answer is the one developed by eighteenth-century theorists of the sublime, discussed in The Postmodern Sublime. Terror, they argued, is the strongest emotion the mind can feel, and when it is experienced at a safe distance it produces not pain but a kind of delight. The storm seen from the shore, the precipice seen from behind a rail: the danger is real enough to stir us and remote enough to leave us unharmed.
On this view horror fiction is a rail. It lets us stand at the edge of the abyss and lean. The pleasure is partly in the fear and partly in the knowledge that it can be stopped by closing the book.
The answer is right as far as it goes, but it does not explain why so many people choose to lean over this particular edge. Safety makes horror tolerable. It does not make it attractive.
Purging and rehearsing
A second family of answers holds that horror does something useful. The ancient theory of tragedy said that drama arouses pity and fear in order to purge them, leaving the audience lighter. Applied to horror, the claim is that we discharge real anxieties through imaginary ones and go home relieved.
A more recent version replaces purging with practice. Fear is a skill, and like other skills it improves with rehearsal. The horror story is a flight simulator for dread, in which we learn what it is like to be hunted, trapped or deceived, and how a person might keep their head. Children's games of chase and the ritual frights of the autumn festival can be read the same way: a community teaching its members to be afraid properly.
Both accounts have evidence on their side, and both share a flaw. They make horror sound like medicine. People who love horror rarely describe it in those terms. They describe it as fascinating.
The fascination of the impossible
That word points to a third answer. The monster, on this account, is above all a thing that should not exist. It violates the categories by which we sort the world: dead and yet moving, human and yet animal, inside and yet outside. Such a being is disgusting because it is impure, and it is fascinating for the same reason. We want to know what it is, where it came from and what it can do.
Horror stories are therefore stories of discovery. The pleasure lies in the investigation, the slow uncovering of the thing in the attic, and the fear and disgust are the price of admission. It is no accident that so many horror narratives are structured like detective fiction, or that the two genres grew up together in the gothic novels of the late eighteenth century.
The monster is above all a thing that should not exist.
The familiar made strange
A fourth answer goes deeper and is less comfortable. A famous essay of 1919 on the uncanny observed that the most disturbing experiences are not of the wholly alien but of the familiar turned strange: the doll that might be alive, the double, the house that is home and not home. Its explanation was that the uncanny is something once known and since repressed, returning in a disguised form.
Later theory added the idea of the abject: what the self must expel in order to exist as a self, the corpse, the wound, the waste. We are horrified by these things because they remind us how thin the boundary is between what we are and what we are made of. And we are drawn to them for the same reason. Horror lets us look, briefly, at the material we spend our lives not looking at.
If this is right, horror is less a flight from reality than an approach to a part of it that ordinary life is organized to hide. In this it resembles the philosophy of transgression discussed in What Transgression Was For, which also held that the forbidden is forbidden because it is charged.
Every age gets the monsters it deserves
The most practical answer is historical. Monsters change, and their changes track the anxieties of the people who invent them. The vampire flourished in an age frightened of contagion and of aristocrats who lived on other people. The creature woken by atomic tests belongs to the first decade of the bomb. The shambling dead crowd, hungry and numberless, arrived with the shopping center and has never quite left it. The possessed child appeared just as parents began to suspect that they no longer understood their children.
The ghost story occupies a special place. A ghost is a piece of unfinished business: a wrong not righted, a death not mourned, a history that the present would rather forget. Places with much unacknowledged history tend to be thick with ghosts. Read in this way, a culture's ghost stories are a register of its debts.
The monster is therefore a mirror, held at an angle. It shows a society what it fears, in a form that can be faced, named and, at the end of the third act, destroyed.
Two kinds of dread
That final destruction marks a division in the genre. One kind of horror is conservative. The monster breaks in, is identified and is driven out, and the world returns to normal, which turns out to have been worth defending. The pleasure is the pleasure of order restored.
The other kind does not restore anything. The thing is not defeated, or it is defeated at too great a cost, or the investigation reveals that the world was never what it seemed. The most radical strain of this horror makes knowledge itself the threat: the scholar who reads too far and finds that humanity is a minor and accidental event in an indifferent cosmos. This is horror as a branch of pessimism, and its pleasures are austere.
The archive is interested in both, but especially in the second. A culture that lives with the expectation of its own ending, slowly, will look for stories in which the end is faced rather than averted. Horror offers that rehearsal. It does not promise that the thing in the cellar will be beaten. It promises only that someone will go down the stairs and look, and that we will be there when they do. That turns out to be a great deal to promise.