Is LSD a great spiritual teacher? Or indeed a teacher at all? My answer is an emphatic "Yes", even though there will always be students who learn nothing from their teachers or misuse what they do learn.

For me LSD is the ultimate psychedelic. It's a tough one – one not to be taken lightly or often. A typical trip lasts eight to 10 hours and there's no respite or way out once you've popped that tiny scrap of blotter in your mouth. I will even admit that on those rare occasions when I take it I feel some deep physiological reaction that makes me involuntarily shaky and afraid just before that fateful moment.

So why do it? Because the fear is worth – a million times over it's worth – the experience.

That experience, as many writers have explained, depends dramatically on the set and setting – on what you expect of the trip, where you are, whom you are with, and how safe you feel. One of the tragedies of drug prohibition is that we have never developed a culture in which young people can learn how to use powerful drugs properly from older, wiser and more experienced psychonauts. I count myself lucky to have encountered such good teachers to guide me with such drugs as LSD, psilocybin, DMT, MDMA and mescaline.

Of course the psychedelics can be just plain fun – the amazing colours, the shifting and moving scenes, the flowers that turn into cats that turn into rabbits that disappear down holes; the sounds that turn into streams that flow away into the sky. But very few people have eight hours of simple fun. This drug, above all, confronts you with yourself. The flickering flowers can turn into scenes of horror and desperation, the coloured-streaked sky into a theatre of unwelcome memories and shame.

For myself I used to face terrible scenes of torture, rape and other kinds of human cruelty. I do not know why, but I found myself imagining them again and again both in meditation and with drugs. Perhaps like most people, I began by fighting them and trying to push them away, but LSD will not let you push anything away. You have to face it. And this is, I think, what makes it the ultimate psychedelic. There is no hiding with LSD. You have to face whatever comes up or be overwhelmed by it.

I faced the fact that I could not blame the drug nor anyone else for my visions, and certainly not for the worst fact of all – that such cruelty has always happened and is happening somewhere even now. Ultimately I confronted the fact that I was not fundamentally different from either the torturers or the tortured, that I had in myself strains of cruelty and hatred that might, under other circumstances, lead me to be the perpetrator as well as the sufferer.

This is just one small example, and everyone's stories are different, but again and again people report that through LSD they learned to know, and accept, themselves. This may be why LSD has such powerful therapeutic effects and can be so helpful for people facing terminal illness.

Our question mentions "spirituality" and whether anyone becomes "kinder and wiser". Surely knowing oneself underlies all these – knowing and accepting your own mind, taking responsibility for what you have done and what you might do. Even simple kindness grows with self-knowledge. When we see ourselves clearly we can see others more clearly, and then it is so very much easier to be kind.

Finally, our question asked "did anyone learn anything about reality from LSD?", "… was it a glimpse – however inadequate – of something real and standing beyond our everyday lives?". I would say that in one sense selves are not "reality", but are invented stories about non-existent inner beings; that what we learn through LSD is precisely about our everyday lives, not something beyond them. But then I would say the same of spirituality. It is not something to be found beyond our everyday lives at all. It is right here and now, and that is precisely what LSD reveals.