“When I close my eyes, they begin to shine, just like the dots and lines,” wrote Czech scientist and former monk Jan Evangelista Purkyně in 1819. “It all ends with a dark rhombus with blunt corners, surrounded by a dull shine resembling a phosphorescent light. A total darkness follows.”
This was no hallucination. But it also wasn’t real. Purkyně was describing phosphenes: the glowing colors, pinwheel forms, and vaguely geometric shadows that appear in our field of vision when we press on our closed eyes or stare too long at bright lights. I would wager that virtually everyone reading this has experimented with their vision in this way. I’d also wager that most of us stopped doing it with any regularity around the time we stopped playing tag.
Yet for Purknyě, it didn’t seem at all strange to imitate this unheralded pastime of childhood. “Who does not remember, if only dimly, such games from that beautiful time?” he asked in his 1819 book Observations and Experiments on the Physiology of the Senses:
One of them, which could keep us busy at a more serious age, is as follows: I stand in bright sunlight with closed eyes and face the sun. Then I move my outstretched, somewhat separated, fingers up and down in front of the eyes, so that they are alternately illuminated and shaded. In addition to the uniform yellow-red that one expects with closed eyes, there appear beautiful regular figures that are initially difficult to define but slowly become clearer.
For Purknyě, this was not simply a visual diversion; it was a rare glimpse behind the veil of consciousness. By staring not at the stuff of everyday life, the material objects beyond the body, but instead looking backwards into the eye, into the mind itself, he found what he believed to be a rich new field of study.
He was right: Today, Purknyě is remembered as a founding father of neuroscience. Yet his ambitions were never fully realized. Purkyně’s stated goal was to contribute not only to what he called the “objective sphere,” but to the subjective as well. He hoped for a “rigorous sensory observation and experimentation on the individual organism”—meaning himself. Neuroscience and psychology emerged as twinned behemoths of the life sciences in the 20th century. Yet today, the intensely narrative, embodied, first-person scientific writing advocated by Purkyně has very few contemporary practitioners—nor does the passion for self-experimentation that actuated his work.
I am often struck, as an historian of pre-modern science and medicine, by the cavalier approach to personal safety in narratives like this. Purkyně’s self-experimentation looks positively tame compared to a young Isaac Newton’s decision to take a bodkin (a large sewing needle) and “put it betwixt my eye and bone as neare to [the] backside of my eye as I could.” This utterly wince-inducing experiment was an attempt to manually alter the interior curvature of the eye and observe the resulting visual distortions. Newton deemed it a success, writing in up in his diary complete with a helpful diagram.
He hoped that his experiments might “sensitize me to experiences of a sort my patients could have,” while also offering “direct knowledge” of the various ways that the structures of the brain mediated consciousness.
Yet my favorite accounts of self-experimentation spring from the strange worlds of early modern pharmacy. By the 18th century, the craft of drug-making was shedding the alchemical mystique cultivated by Paracelsus. Yet it continued to attract an assemblage of fascinating eccentrics, from the pirate surgeon Lionel Wafer to a young John Keats.
Purkyně, too, was an ardent student of pharmacy; one of his most famous cases of self-experimentation involved taking a dose of digitalis that was seven times the amount lethal amount for cats. The drug temporarily blinded him. He also was among the first to observe the psychoactive properties of nutmeg. As Lawrence K. Allman describes in his entertaining history of medical experimentation, “he took varying doses of the drug on three successive mornings, describing its hypnotic effects and the unusual euphoria that lasted several days after he took it with wine.”
I WOULD ARGUE THAT there was something singular about the era when Purkyně was performing these feats. As Richard Holmes described in his lovely book The Age of Wonder, the first two decades of the 19th century were energized by a new sense of the individual and the imaginative power of the human mind. This brought “a new imaginative intensity and excitement to scientific work,” Holmes writes. “It was driven by a common ideal of intense, even reckless, personal commitment to discovery.” In other words, scientists of the Romantic Era strove for the same “derangement of the senses” that a teenage Rimbaud would declare to be the proper aim of poets. They ventured into the air in homemade balloons, shocked themselves with early (yet powerful) electric batteries, and enthusiastically consumed dangerous amounts of experimental chemicals—all in the name of wonder, and of science.
The greatest chemist of the Romantic Era, in fact, was also one of his era’s most ardent drug takers. Sir Humphry Davy didn't invent nitrous oxide, otherwise known as laughing gas, but he was among the first scientists to experiment with it extensively. He was also among the first to treat it like a recreational drug. Davy and his coterie were such aficionados of the new gas that they built "an air-tight breathing-box, of the capacity of about nine and one-half cubic feet" in which to enjoy it. Davy recorded falling into a "semi-delirious trance" in which he "existed in a world of newly connected and newly modified ideas. I theorized; I imagined that I made discoveries." In the end, however, despite the insights that appeared to grip him while under the influence, he was left with a sole, and, sadly, rather feeble nitrous oxide-induced insight. As Davy put it, “Nothing exists but thoughts!"
As science developed into a professional vocation pursued in institutional settings, the use of one’s own body as an experimental laboratory became less common. Yet it didn’t disappear. Richard Feynman, the brilliant Cal Tech physicist who was one of Oppenheimer's youngest recruits at Los Alamos, left a memorable account of self-experimentation in his memoirs. Feynman, who cultivated a beatnik persona even after winning the Nobel prize, had long “wanted to see hallucinations.” But he was afraid that drugs would negatively impact his physics work. He was intrigued, then, by an offer from John Lilly, an eccentric cetacean researcher who is today most famous for administering LSD to dolphins. Feynman recalled how he visited Lilly at his lab in order to spend time in a sensory deprivation tank. After sitting through what Feynman called Lilly’s "mystic hokey-poke about different kinds of lights that have different kinds of influences" (shades here of the fascination with synesthesia and color of an earlier generation of scientific mystics), the time had come to enter the tank.
The first try failed to yield hallucinations. On his second attempt, however, Lilly introduced him to “a man billed as a medical doctor, who told me about a drug called ketamine.” Feynman took a starter dose of the ketamine, which would later win infamy as a club drug. He remembered that “the drug had quite an effect on my vision; I felt I couldn't see clearly.” He had “a feeling of complete disorientation” and began staring intently at his hands.
Jan Evangelista Purkyně’s drawings of phosphenes. (Photo: Public Domain)
After these early deprivation experiments, Feynman wrote, “I had hallucinations almost every time, and was able to move further and further outside my body.” Feynman belonged to the imaginative—we might even say mystical—branch of theoretical physics epitomized by Oppenheimer (he of the cryptic Vedic utterances) and Einstein, with his dream visions of hitching rides on light beams. It was natural, then, that Feynman would be fascinated by the potential of these out-of-body hallucinations. Yet in the end he decided they weren’t true scientific experiments, contra Lilly, because their subjective nature made them overly susceptible to the expectations and influences of the individual.
For the human sciences, however, this subjectivity was not necessarily a bad thing. Around the same time that Feynman and Lilly were experimenting with ketamine, a young Oliver Sacks—then a young medical resident in Los Angeles—was using himself as a human guinea pig. In a recent New Yorker memoir, Sacks remembered his mid-’60s flirtation with recreational drugs ranging from amphetamines and LSD to Artane, "a synthetic drug allied to belladonna" that provoked a profound state of delirium. Among other things, Sacks recalls his rapturous (and LSD-fueled) hallucination of "a huge, trembling, pear-shaped blob of the purest indigo." Here was the color "that Giotto spent a lifetime trying to get but never achieved,” Sacks writes. “It was the color of the Paleozoic sea, the color the ocean used to be.” When the vision subsided, he felt “an overwhelming sense of loss.”
By staring not at the stuff of everyday life, the material objects beyond the body, but instead looking backwards into the eye, into the mind itself, he found what he believed to be a rich new field of study.
A frightening encounter with morphine ultimately turned Sacks away from the potentially self-destructive path he was on. Having injected himself with the drug, Sacks lay on his bed and hallucinated a “microscopically detailed battle scene” taking place on the sleeve of his silk dressing gown. There were “tents of different colors ... gaily caparisoned horses, soldiers on horseback,” he remembered. “I realized that what I was gazing at from my aerial viewpoint was Agincourt, late in 1415.” When he stirred from his stupor, he realized he’d been watching the scene for over 12 hours.
Yet despite his frightening brush with IV morphine, Sacks also manages to offer up a cogent defense of self-experimentation. It is all too easy to treat science as a platform that allows the observer to hover over the messiness of life, unobserved and untouched. Yet the fact is that Purkyně was right: We can never fully disentangle the life sciences and medicine from our subjective existence as living beings. To treat a patient involves imagining what it would be like to be that patient. Sacks, more than many of his peers, knows this. And his self-experimentation took place in this context: He hoped that his experiments might “sensitize me to experiences of a sort my patients could have,” while also offering “direct knowledge” of the various ways that the structures of the brain mediated consciousness.
Wordsworth famously imagined Newton as a disembodied force, “a mind for ever / Voyaging through strange seas of Thought, alone.” Yet Newton was a human being, not an interstellar probe. The lack of regard for personal safety that lay behind Newton’s sewing needle—or Sacks’ morphine needle for that matter—is not for everyone, but these episodes offer an important reminder of the difficulty of isolating science from human bodies. By experimenting on ourselves, we’re forcibly reminded of who we are: not just a brain, but an optic nerve, a pair of eyes, ears, teeth, hands, and feet, all bound together by sinew, bone, vein, and nerve. A fleshy and awkward amalgamation, weak and easily harmed—but also capable of profound empathy, resilience, and understanding. By embodying science, perhaps self-experimentation humanizes it, too.