Today I am going to speak about the use of psychoactive drugs for spiritual purposes which is the subject of a new book which I am currently working on.

My first LSD trip, in 1966, was a profound experience which I believe changed the course of my life. At the time I was an engineering student, and I saw that my aims and very existence were insignificant on the scale of universal time and space. The immediate effect was to make me depressed by undermining my belief in myself, but it lead me to search for something more meaningful in life, and I tried out various spiritual teachings.

The odd thing is that I never regarded that LSD experience as spiritual itself. I put this down to the fact that I had rejected religion after spending 5 years at a boarding Catholic school run by monks, and regarded anything 'spiritual' as religious. But then I have recently heard the word spiritual used by many other people who I would not expect to, like ravers watching the sun rise. So perhaps there is a widespread spiritual emergence, or perhaps the experiences are the same but it has become more acceptable to describe them as spiritual.

More recently I had an LSD experience which took me by surprise. It was a perfect situation: I was with my wife and it was a fine summer's day, we were out in the country in a beautiful secluded place, and I was in love. For a while we time travelled together, seeing into one another at all ages we ever were and will be. I felt very whole and loved.

Then it all changed and my trip went its own way. I felt as though I had let go completely for the very first time, and letting go meant allowing my essence to flow back to where it belonged, back to its source. It was like coming home but more so, and a great relief to let go. It felt unquestionably "right". Tears streamed down my face as I cried with joy.

We were camping, and that night I stayed awake, savouring the experience and trying to keep in mind without using words to describe it. I valued the experience so much that I did not want to describe it in words that might debase it, so I tried hard to think of ways of identifying what happened so that I could recall it, yet without using words with a connotation, like "soul".

I also contemplated the experience, and it felt "Natural" in that I felt sure that this was something essentially human, and that it had been experienced by people of all cultures throughout time. In fact, I had the insight that mankind invented religions in order to provide an explanation, or framework, for such experiences, so as to give them validity in our normal consciousness. That is what religions are for, and why people believe in them. I saw how my experience related to the Christian teachings of everlasting life, with God in the other realm of consciousness and Jesus as the link between realms of consciousness.

When we came home I avidly searched for Peak Experience and Spiritual Experience on the Internet, and before long had satisfied myself that I had had the 'real thing' and that it had similar qualities to the mystical experiences of the saints.

Well, that might seem like a big claim. How can you tell, and anyway, what is spiritual?

Nearly every religious leader will tell you that drugs cannot induce a true spiritual experience.

They will usually say its an illusion, or not at the same level as the real thing. The more liberal ones may say, OK its the same, but it doesn't have the same value as an experience gained the hard way.

They - and that includes trendy New Age teachers of meditation, too - also say that taking drugs will destroy years of spiritual work. Well, once I took ecstasy with a woman who followed a Sufi teacher and was very worried about this, but as it came on she shouted "What fools they are!" Far from harming her spirituality, she saw that ecstasy put her right in touch with it.

But how can we really know, how can we truly compare the drug induced experience with that experienced by Ignatius do Loyola or any of the other saints revered by the religions? It sounds like you could argue for hours without any way of finding out for sure whether the drug-induced variety was as good.

Surprisingly, there was a proper scientific experiment carried out to answer just that question. It was called The Good Friday Experiment, as it took place on Good Friday at Boston University. At that time, in 1962 there was no law against psychedelic drugs, or even public prejudice about them. In fact LSD was seen as an exciting new drug with great potential and in Britain over 10,000 psychiatric patients were treated with it.

The subjects were postgraduate students studying theology at Boston University, and the researcher was called Walter Pahnke. None of the students had taken a psychoactive drug before, so they were prepared by attending classes given by experienced assistants who were careful not to use any religious terminology. This was principally to allay their fears and encourage them to go with the experience.

The Good Friday service was conducted by a well known charismatic preacher in the main chapel of the university, while the experiment took place in a chapel linked by a loudspeaker.

One and a half hours before the service, all the 20 volunteers were given identical looking capsules, but half contained psilocybin mushrooms while the others were given placebos. This was in standard double blind fashion: neither researchers nor participants knew who had the 'real thing'. But this was even cleverer than usual, as the placebo was "active": it contained a drug which was not psychedelic but produced a feeling of warmth and tingly skin. The result was that all participants felt something, and were equally expectant.

Immediately afterwards the participants were given a questionnaire to evaluate their experience, and again six months later. The result was that eight out of ten of those who had psilocybin were evaluated as having had a strong spiritual experience. None of the controls had high scores, but some did appear to have had mildly spiritual experiences. This may have been due to "contact high", or simply that they would have had them anyway given the set and setting.

Well, you may well ask what kind of questions could identify a spiritual experience! This is what they looked for:

Unity: loss of ego or sense of underlying one-ness. This meant remaining fully conscious of surroundings while becoming unaware of oneself; or it could mean being that all living things shared the same energy.

Transcendence of time and space. The experience was not ruled by clock-time or geographical location. Sometimes this was described as eternity or infinity.

Sacredness, feeling of awe. No religious beliefs or terminology need be involved, but the state "was capable of being profaned".

Paradoxicality was another quality, and meant the experience had to have elements that are logically contradictory.

Ineffability, or the inability to describe the experience adequately in words.

Transiency: the experience is transitory, does not last.

Lastly, they included a test to see whether the experience produced positive life-changing behaviour, and they defined this quality as: Persisting Positive Changes in Attitudes and Behaviour. This was assessed at the six month follow up.

The results clearly showed that the drug could induce valid spiritual experiences under the conditions of the experiment.

Time Magazine summarised these results by saying that: "All students who had taken the drug psilocybin experienced a mystical consciousness that resembled those described by saints and ascetics". This was actually an exaggeration, as one subject had freaked completely and was tranquillised!

The next question is: but does it last?

A follow up was carried out about 25 years later by Rick Doblin who runs an organisation promoting research into positive uses for psychoactive drugs. He managed to get 17 of the original 20 subjects to answer the same questionnaire again. Many of these people had been clergymen for over 20 years, and some had had spiritual experiences since, both with and without drugs. Anyway, I will read his report verbatim:

"All psilocybin subjects participating in the long-term follow-up, but none of the controls, still considered their original experience to have had genuinely mystical elements and to have made a uniquely valuable contribution to their spiritual lives. The positive changes described by the psilocybin subjects at six months, which in some cases involved basic vocational and value choices and spiritual understandings, had persisted over time and in some cases had deepened.

The overwhelmingly positive nature of the reports of the psilocybin subjects are even more remarkable because this long-term follow-up took place during a period of time in the United States when drug abuse was becoming the public's number one concern, with all the attendant social pressure to deny the value of drug-induced experiences. The long-term follow-up interviews cast considerable doubt on the assertion that mystical experiences catalysed by drugs are in any way inferior to non-drug mystical experiences in both their immediate content and long-term positive effects".

So much for the scientific evidence.

At the beginning, I mentioned at the beginning about religious leaders coming out strongly against drugs. Well, there are some exceptions to the rule, and in Ecstasy and the Dance Culture, I interviewed a rabbi, two Zen monks and a Benedictine who used drugs - ecstasy in fact- for spiritual purposes.

The Benedictine had used Ecstasy two or three times a year in the US since before it was illegal. He explained to me that 'prayer' normally meant trying to pray, but that its aim - communicating with God - was rare. As a monk he would try to pray every day, but that simply meant making the effort to pray. Fortunately, his religion regarded trying as OK even without success, but on ecstasy the 'trying' changed into "opening up a direct link with God". This spiritual experience was not only very valuable in itself to him, but, as he put it, "provided a reservoir of strength to call upon in times of need". It also made prayer easier at other times, as familiarity with the experience meant he knew what to look for, and provided confidence that it was attainable.

I asked the obvious question: "What do you think about people taking E in nightclubs?" He told me he was shocked, and that it was profane for hedonists to use the drug. Well, this showed up his naivety, but I was also touched as it showed how sincere and focused he was in his own use of the drug.

The rabbi was more worldly. Almost his first words were that a young person today had a much better chance of a spiritual experience in a nightclub taking drugs than by attending a church or synagogue! He went on to say that the major religions had forgotten their original purpose in seeking spirituality, but he believed that instead spiritual openings were occurring among drug users which would lead people on to richer lives.

The Zen monks were from different schools and did not know each other, but both taught meditation and both said that the majority of their students came as a result of spiritual experiences on a drug, usually LSD. Yet their hierarchies still laid down that such drugs must not be used.

There views were upheld by the Buddhist magazine Tricycle, which published a special issue last autumn called "Psychedelics, Help or Hindrance?". It contained a series of articles on this topic, both for and against, although the general trend was positive towards the use of psychedelics. They also published a readership survey. The results showed that psychedelics were considered to be useful by the old hippy generation and those under thirty, but those in between were against drugs. I think that this mirrors society's views in general: there has been a renewal of respect for psychedelics.

I have been talking about present day spiritual uses of psychoactives. But its important to realise that the use of drugs for spiritual purposes is nothing new. Rather, the present interest is perhaps a revival of spirituality as it was experienced before religion became so institutionalised.

It's also worth remembering that there have been many previous wars against drugs, and that many spiritual practices using drugs have been eliminated through persecution. In India they used Soma; in Europe we had witches who made use of mushrooms and toad skins until they were persecuted out of existence; in Siberia the Communists wiped out the shamans who used fly agaric. In North and South America the Christian missionaries are still actively trying to eliminate traditional shamans and their use of psychoactive plants by saying they are devil worshippers. This not only continues, but with renewed vigour by some missionaries whose aim is to eliminate paganism by the millennium.

On the other hand, there is renewed interest in these ancient spiritual practices by Westerners, and some religions have recently emerged from the rain forest using the plant drug ayahuasca incorporating both Christianity and traditional shamanistic traditions. Some, like the Santo Daime and Unaio do Vegetal, have even spread to Europe.

It is this renewed belief in the value of spirituality which is helping to preserve and revive these ancient uses of psychedelics, and to give back self respect to tribes who have been brainwashed by the missionaries. In addition, new spiritual rituals are being created based on new synthetic psychedelics.

Finally, I want to end by telling you about one of the Zen monks I mentioned earlier. He was fifty when he took up Buddhism, and studied under a strict Japanese master. The teaching consisted of the master giving tasks called Koans, such as to "understand the sound of one hand clapping". Usually the student would spend hours contemplating, then report back to the master only to be sent away to try again. But on E, he got the answer straight away, and as a result made rapid progress and soon became an abbot. He didn't think of it as cheating, but simply that he had found an easier way of learning what took the others longer.

I invited him to a private party in a big country house where nearly everyone was on E. He was seventy, and before this had only used ecstasy by himself, usually on the second day of a seven day meditation, but he was curious to see the effect at a party. He was at first reluctant to go inside, holding fingers in his ears because he couldn't stand the noise. But eventually he got into it and then exclaimed: "They are meditating! These people have stopped their internal dialogue and yet are fully aware in the present. That's what we teach in walking meditation, yet these people are doing it without realising!"

Next day he said that the experience had provided him with the insight that his school of Buddhism had got it wrong. They had assumed that Westerners were to extrovert and so had concentrated on discipline, but in fact those who were attracted to the school were introverts, and they would greatly benefit by going to a rave and taking ecstasy!

He left me feeling optimistic that the dance/drug generation has got it right!