A new edition of William Burroughs' book 'The Yage Letters' reveals how the writer was transformed by a trip to South America in search of 'the ultimate fix'. Tim Cumming reports

"Yage may be the ultimate fix," the writer and countercultural icon William Burroughs concludes at the end of his first novel, Junky, published in 1952. The man they called "el hombre invisible" is perhaps the greatest in the 20th century's gallery of cultural extremists; his novel Naked Lunch became the plat du jour of Sixties counterculture, and his revolutionary "cut-up" technique - on tape and film as well as on the page - presaged the viral, wireless, sampling culture of our own century by decades, and has influenced countless artists, writers and musicians through the decades.

More than half a century later, yage, the psychotropic jungle vine also known as ayahuasca ( "the vine of the soul" ) retains its status as the most mysterious and powerful of natural hallucinogens. Burroughs' book about his search for the "ultimate fix", The Yage Letters, possesses an equally strange and secret history. Published in 1963 but written a decade earlier, it has long been seen as a fascinating curio in the Burroughs canon, yet a new edition of the book, edited by Oliver Harris, places it more centrally in the list of key Burroughs texts.

Harris introduces the original edition, which was based around Burroughs' correspondence with the poet Allen Ginsberg, with an in-depth survey of the book's fragmented history, and expands the 96-page text with extensive appendices of new material, including unpublished articles by Burroughs that are considerably more revealing about his experience and understanding of yage than much of what was published in the book. The Yage Letters Redux is rounded off with previously unpublished excerpts from Ginsberg's journals from the trip he made in Burroughs' footsteps in 1960.

It was a harried and junk-sick Burroughs who left Mexico in early 1953, a little over a year after he had accidentally shot and killed his wife, Joan Vollmer, while attempting a "William Tell" act - firing at a glass she had balanced on her head. Racked as much by fear and guilt as by opiate withdrawal, and leaving virtually unprepared for what was to come, the author headed south to Colombia and Peru, in search of the ultimate yage fix - and a way out of his addiction.

Yage has been used for thousands of years - a ceremonial cup dating to 500BC is held in a museum in Quito, Ecuador. More recently, yage-based religions, such as the Uniao do Vegetal and Santo Daime churches, have battled in court to preserve their right to sacramental yage use, while drug companies such as Pfizer have embarked on legal battles of their own to exploit its active properties.

At the time of Burroughs' trip, little was known or understood about yage. It was lucky that on his arrival in the Putumayo region of Colombia in 1953, in search of the right medicine man, he encountered Dr Richard Evans Schultes, the famed ethno-botanist who would also contribute much to our understanding of the drug.

Both were Harvard men, and despite Schultes' evident misgivings at Burroughs' unorthodoxy, the two embarked on a 1,000-mile expedition that led to the author's first overwhelming contact with yage: he overdosed and went into convulsions. A second, more ecstatic series of encounters, in Pacullpa, Peru, would in due course unleash some of the most extreme works of fiction ever published.

The letters to Ginsberg are a restless mixture of anthropology, travelogue, paranoia, poetry, epiphany, cut-ups, satirical junkie cynicism and epistolary novel. "I stopped here to have my piles out," the first letter begins in January 1953, from the aptly named Hotel Colon in Panama, and much of what follows is more about the misadventures of the journey than the destination.

Until, that is, the letter describing the "composite city" - a vision that is uniquely Burroughsian, and runs through much of his work. "Minarets, palms, mountain, jungle. A sluggish river jumping with vicious fish, vast weed-grown parks where boys lie in the grass or play cryptic games..." In the letter's pin-sharp panoramas lay the seed not only of Naked Lunch but of the cut-up novels that followed. The Soft Machine, The Ticket That Exploded, Nova Express: each of them, arguably, has its roots in the riotous, disorderly effects of the South American vine.

In a detailed introduction, Harris reveals how The Yage Letters began as a manuscript typed on Burroughs' return to Ginsberg's apartment in New York in the autumn of 1953. Less than a fifth of the final manuscript came from actual letters. It's typical of Burroughs that what purports to be a casual and fragmentary travelogue is in fact a much more arranged and reconstituted entity. For Harris, it demonstrates that it was much more than a casual correspondence preserved for posterity: "It's the developing of his imaginative landscape out of the real one."

The book was finally published by Lawrence Ferlinghetti at City Lights, who expanded the text with Ginsberg's 1960 letters from Peru, where, seven years after Burroughs' trip, Ginsberg, too, encountered the awesome spirit of the vine. "I light cigarette, blow a puff of smoke over cup, and drain," he writes. "Lay down expecting God knows what other pleasant vision and then I began to get high - and then the whole fucking cosmos broke loose around me, I think about the strongest and the worst I've ever had it."

Not that he hadn't been warned. "This is the most powerful drug I have ever experienced," Burroughs writes in an unpublished article he sent to Ginsberg in 1956. "Yage is not like anything else. It produces the most complete derangement of the senses." These include intense sexual hallucinations, flashes of phylogenetic memory, and full out-of-body experiences. "There is a definite sense of space time travel that seems to shake the room," he notes, and posits that the extreme nausea that accompanies the visions is a form of "time-space motion sickness".

The active ingredient in yage that produces visions is harmeline, once called telepathine, because of its supposed telepathic properties. Harmela alkaloids are present in the pineal gland, the "third eye" in the forehead, and it seems that out of all the psychotropic drugs, yage reaches deepest into the psyche, which may explain why so many users report near-identical Garden of Eden-like visions, as if there were some direct connection to the collective human image bank.

The bark of the vine is cut into lengths and stripped, pounded and boiled in water with the leaves of a plant called chacuna by the Indians, and which Burroughs was the first to correctly classify as Psychotria viridis. This is essential to achieve the full hallucinogenic effect, for without the DMT in the chacuna leaves, the harmeline alkaloids in the vine remain inactive.

The Yage Letters marks the point when Burroughs moved full-time into his own, fully realised universe.

'The Yage Letters Redux' is published by City Lights, price UKP 9.99
MAP posted-by: Richard Lake