Stephen Asma’s On Monsters offers an enjoyable, if somewhat fractured, survey of monsterology through the ages. Monsters pre-date horror films and ghost stories. The concept of the “monstrous” has always been part of human experience. Each age understands monsters differently. The first half of On Monsters explores evolving understandings of monsters. In general, monsters stand outside normal experience. Monsters personify those things we do not or cannot understand. Monsters are a manifest acknowledgement of the limits of human understanding. As these limits change, our monsters change. Monsters dwell in the places we believe to be unknowable.

For the ancients, the unknowable places were empty spots on the map. This gave us the great sea monsters and terrible, cannibalistic races that inhabited the oceans and unfamiliar continents.

In Biblical times, monsters were agents of God, mysterious and unfathomable. Think Leviathan.

The earliest monsters were thought to be part of the natural order. They walked among us and lived in places we could not or should not go.

Medieval monsters were supernatural – witches and demons. They didn’t live in a special place of their own. They lived everywhere and regularly intervened in the lives of the non-righteous.

With the Enlightenment, came the medical fascination with mutation and physical aberration in the human family. “Monsters” were no longer mythical. They were miscreants, captured and preserved in jars, and offering a measure of enjoyable frisson for collectors of oddities and the paying customers of these collections. The Mutter Museum is one of the most famous collections.

Over the past 200 years or so, our ideas about monsters have become internalized and have represented what we believe we cannot understand about ourselves. Modern times have been preoccupied with psychological monsters, like serial killers, tyrants and sociopaths.

Asma is at his best theorizing on the horror genre as the “art of human vulnerability”. He is particularly clever in his discussion of slasher films and “torture porn” and how they either explore or exploit the understood limits of human vulnerability to either empower or debase.

The second half of the book is less successful. Asma struggles with contemporary notions of the monstrous in the fields of cosmetic surgery, terrorism, robots and cyborgs. This is fertile ground for exploration but he does not bring these threads to any satisfying conclusion.

For most of human history, monsters were aberrations from the intended order of things. With the advent of biotechnologies and cybernetics we are faced with the possibility that there may be no final intended order of things. If there is no intended order to things, then some would suggest there can be no monsters. Everything becomes monstrous. Asma does not reject the promise of the new technologies to improve the quality of human life. But neither is he willing to abandon the concept of the monstrous as a useful indication of something still somewhat poorly defined.