One of the more exciting scholarly developments of the century to date has been the growth of studies – previously hindered for too long by legal barriers – into mystical experiences induced by psychedelic drugs. In a landmark 2006 experiment, rigorously controlled and double-blind, Roland Griffiths’s research team at Johns Hopkins University found that people given high doses of psilocybin – the active ingredient in magic mushrooms – typically had experiences they described as “having substantial personal meaning and spiritual significance”, and bore several other characteristics in common with a certain kind of non-drug-induced mystical experience: a sense of merging with ultimate reality, a nondual sense of the unity of reality, a sense of awe or sacredness. This sort of mystical experience, it seems, can be chemically induced.

Do such experiences, whether or not drugs are involved, tell us anything about reality – the reality they are supposedly experiences of? In How To Change Your Mind, Michael Pollan notes that those who have had such experiences often feel certain about them. (None of my reservations about Pollan’s approach to food apply to his work on drugs.) Says one: “This was no dream. This was as real as you and I having this conversation. I wouldn’t have understood it either if I hadn’t had the direct experience.” So they are convinced that the result is real.

However, Pollan notes further that those who have had such experiences usually struggle to describe them. In summing up what he learned from his psilocybin experience, Richard Boothby, a philosophy professor, could do no better than “Love conquers all” – fully recognizing that this is the sort of insight that “one associates derisively with the platitudes of Hallmark cards.” And Boothby was more articulate than most – often they just said the equivalent of “You had to be there.” Rationalist philosophers might see all this as evidence that those having these experiences are fooling themselves: if they can’t describe it, how real can it be?

Yet consider the experience of Thomas Aquinas. Typically considered the greatest of all Catholic theologians, Aquinas would be a strong contender on lists of the greatest philosophers of all time, revered for the subtlety and care of his arguments – and still influential in contemporary ethics, in thinkers ranging from eccentric Catholics like Alasdair MacIntyre to secular philosophers who embrace his “doctrine of double effect“. But Aquinas never finished his great work, the Summa Theologica. Why? According to the biographers William of Tocco and Bartholomew of Capua, something happened to him while saying his Mass in December 1273, after which he claimed that “All that I have written seems to me straw compared with what has now been revealed to me.” But what was it that was revealed? That, the famously wordy Aquinas never told us. He would not put this experience into words – and yet it seemed orders of magnitude better to him than all the magisterial volumes he had actually composed.

Indeed, when William James tried to define mystical experience in The Varieties of Religious Experience, the first characteristic he came up with was ineffability: “The subject of it immediately says that it defies expression, that no adequate report of its contents can be given in words.” This is a feature that many such experiences seem to share, whether induced through drugs or received a different way.

James and Pollan both note that, when one does try to put the insights from a mystical experience into words, it is common for those insights to seem banal, uninteresting – a platitude. (“Love conquers all” is a great example.) Yet platitudes are underrated! We human beings are not computers, who process every sentence using the same logic. Words affect us in different ways in different contexts. When Sāriputta and Moggallāna heard the sentence “Whatever can arise can cease”, it instantly liberated them from suffering, whereas you and I just read that same sentence and it probably did nothing for either of us. Taken on its own, the sentence seems trivial, but in the right context it can expose hidden depths of supreme importance. And that context isn’t necessarily just linguistic. As far as I can tell, this is what makes meditation or something like it essential to the Buddhist path: it’s not enough just to assent to Buddhist propositions, you need to recognize them deep down. Only that way will they affect your emotions, which are more primal than mere cognitive judgements. So, there is a sense in which such an experience doesn’t actually teach you anything new; what it teaches you may be to see, and more importantly feel, your existing ideas in a new way. In Pollan’s words, “what was merely known is now felt, takes on the authority of a deeply rooted conviction.”

I would not say that I’ve had such an experience myself – not yet, anyway. My experience on ayahuasca this summer was powerful in a number of ways, but not in the ways described by Griffiths and Pollan. (Notably, my experience did feel somewhat like a vivid waking dream, without the sense of certainty they describe.) But the experiences Griffiths and Pollan describe seem to me worthy of respect. It’s not just the certainty felt that the experience was real, but its ability to transform people’s lives afterward. Neither means that the people were necessary right about what their experiences say about reality – but we should also not be too hasty in saying they are wrong.