TALKING about your drug experiences is like talking about your dreams: it may be personally rewarding, but for others it's a bore. As with dreams, the insights, visions and revelations that accompany some drug experiences can provide new perspectives on your life and help you to "know yourself".

The person on the receiving end of your dope stories, however, more times than not stifles an impatient "So what?" and wonders when you'll get to the point. This is the paradoxical character of drug experiences: their profound subjectivity is a barrier to communication.

A handful of writers, De Quincey, Huxley, Burroughs and a few others, managed to cross this threshold and master the art of "trip-lit". But most accounts of psychedelic journeys into inner space boil down to a less than informative "Awesome, man". This may let us know that the voyage meant a lot to you, but it still leaves us in the dark as to what was so meaningful about it.

Julian Vayne argues that drugs can be an effective tool in selfexploration, and provides some useful theoretical scaffolding in understanding exactly what a "drug experience" is. Vayne argues that the mainstream materialist view of drugs is incomplete, and he makes clear that the chemical analysis of various substances like LSD, ecstasy, cannabis and other popular items is only half the story.

The importance of "set and setting" and our cultural expectations about exactly what a particular drug is supposed to do are equally crucial; our imagination and anticipation about what we will encounter after ingesting a magic mushroom are at least as significant as the psilocybin housed in the fungus itself.

Drug experiences, Vayne contends, are learnt. They aren't simply a matter of an automatic chemical reaction between my bloodstream and the toxin I've introduced to it.

The author makes a similar point about how the same drug may have very different effects on different people. A lump of hash may lift a Baudelaire into poetic reverie, but the same lump may only sink the rest of us into befuddled sleep. LSD advocates in the 1960s made a similar discovery when it became painfully clear that taking acid didn't automatically make people more spiritual and enlightened. The trip, good or bad, is as much in ourselves as in the drug. Although Vayne has written several books on occult subjects, the occult or magical sensibility informing the book is curiously faint.

The tone of Vayne's book is academic, and a great part of it is devoted to the mechanics of how drugs interact with our neurochemistry. He's also at pains to anchor drug experiences in the post-modern discourse of transgression. This makes for a text in which Derrida turns up almost as often as Aleister Crowley. It's refreshing to find occultism rubbing shoulders with other viewpoints, but the narrative is sometimes burdened with digressions on the Derridian "trace" and other notions.

Vayne's most interesting insights come with his discussion of autism and schizophrenia as two poles of human consciousness: one an impenetrable contraction of the ego, the other a debilitating exposure to the chaos of the unconscious.

Vayne makes a good argument that, rather than exceptional conditions, autism and schizophrenia are the extremes between which our "normal" consciousness fluctuates; drugs for him are a means of compensating for imbalances between the two. Like many writers on mystical subjects, Vayne sees western culture as veering too much into an ego-bound autism. Hence the virtue of hallucinogens in providing a kind of controlled schizophrenia to even things out.

Pharmakon first appeared as an e-book a few years ago and it's a pity that, in releasing it in print form, the publisher didn't bother about editing. The text is full of typos and misspellings and suffers from an aversion to punctuation; this makes for a bumpy read.

There are also some howlers.

Theophile Gautier and the other members of the Club des Haschischins ate their cannabis, they didn't smoke it. Julian Jaynes was a psychologist, not a historian.

And I imagine that the "occultist W B Leadbeater" is an amalgam of W B Yeats and C W Leadbeater.

If you're arguing that drugs can be a tool in self-actualisation, it's a good idea not to provide material for jokes about how stoned you were when you put your book together.