In the 1960s, intellectuals such as Aldous Huxley were fascinated by the effects of LSD, but today most professors are far too worried about respectability and tenure to investigate psychedelics themselves. Which is somewhat ironic, given that the field of Western philosophy has a huge debt to psychedelics, according to Peter Sjöstedt-H, a philosophy doctoral candidate at University of Exeter who has written a book on the philosophical significance of drugs. In fact, one of Plato’s most-cited theories may have been a direct result of hallucinogenics.

In Plato’s Phaedo, the philosopher says he was inspired by the Eleusinian Mysteries, an ancient religious ceremony where participants took kykeon. It’s widely believed (thought cannot be definitively proven) that kykeon was a psychoactive substance, which would explain the visions that participants experienced during the ceremony. Sjöstedt-H notes that Plato references the Mysteries and “seeing that his body is but a shell, which one can escape through these experiences,” before he introduces his landmark notion of substance dualism: Namely, the idea that body and soul are distinct.

“Under psychedelic experience, you can completely lose the link between ‘you,’ yourself as a body; and ‘you,’ yourself as the person that you think you are, including your memories,” says Sjöstedt-H. “There’s this loss to the self, and the self is often associated with the body, so I can certainly see why a psychedelic experience would incline one towards a more dualistic view of the world.”

If the Mysteries did indeed involve psychedelics, Sjöstedt-H says we can credit them with inspiring some of the greatest and most influential thoughts in history.

“[Alfred North] Whitehead famously said, ‘Western philosophy is a series of footnotes to Plato.’ If Plato was inspired by psychedelics, then the whole of the Western canon is unwittingly inspired by these experiences,” Sjöstedt-H adds.

More than 2000 years later, Sjöstedt-H believes that it’s absolutely essential to understand psychedelic experiences in order to develop a thorough philosophy of how the mind functions. “You haven’t fully explained the mind until you’ve explained all facets of it,” he says.

Psychedelics create “a peak type of mind, a peak type of experience” and, as such, they’re a valuable consideration in certain philosophical mysteries, like understanding the relationship between the brain and the mind. Research has shown that parts of the brain are less active during psychedelic experiences, which is the inverse of what one might expect for a period of heightened consciousness. This finding highlights the complexities of explaining how the mind and brain relate, which is one of the great philosophical challenges, known as “the hard problem” of consciousness.

But even among non-philosophers, Sjöstedt-H believes that a lifetime without trying psychedelics is unnecessarily narrow. “Experientially, it would be a pity to live one’s life without having experienced the potentials of the human mind,” he says. “It’s a bit like living in the same country all one’s life and not going on holiday, not seeing the rest of the world. It’s a loss. By having this experience, one experiences more reality because the mind is part of reality.”

He adds that psychedelics can open your mind to new beliefs, increase appreciation for nature, and lead to completely new feelings. As well as being “intellectually stimulating,” Sjöstedt-H says that psychedelics can be a “sublime” aesthetic experience.

Despite the potential benefits, Sjöstedt-H does not believe that everyone should take psychedelics. Nor does he insist, as was common in the ‘60s, that doing so would lead to world peace. When I told Sjöstedt-H that I was too afraid of my own mind to risk exploring its suppressed depths, he agreed that was a valid concern. Bad trips are a serious risk, and more troubling for some than others. Those who are religious (and so would be more profoundly affected by visions of devils, for example), are especially anxious, or have suffered serious traumas, could well find psychedelics to be harmful rather than enlightening.

We have no clear idea of how psychedelics produce their effect; but it’s thought that changes in brain activity create an altered state of consciousness. For those who are able to have a positive experience on psychedelics, Sjöstedt-H says taking the drugs can be as profound as reading Nietzsche. Both the philosopher and the substance lead to questioning one’s cultural values and societal rules, he notes.

Arguably, taking psychedelics can also enhance the experience of reading philosophy; Sjöstedt-H points to the psychologist and philosopher William James, who claimed to only fully understand Hegel after taking nitrous oxide. (Though drugs haven’t improved Sjöstedt-H’s own reading of Hegel.)

Though other philosophers are interested in hearing about his work and experiences with psychedelics, Sjöstedt-H acknowledges that few are prepared to try the drugs, at least for now. Many are worried about the psychological risks, put off by their illegality, or simply don’t want to mess with their brains.

But Sjöstedt-H hopes that growing acceptance of the drugs will allow for a study of how psychedelics could shape the opinions and outlooks of great contemporary thinkers. They were good enough for Plato, after all.