Beyond their visual qualities, mescaline’s hallucinations posed profound philosophical questions. During the mid-1930s three prominent writers and thinkers left records of their experiments with it. In 1934 and 1935 respectively, Walter Benjamin and Jean-Paul Sartre participated in the now-familiar modus operandi of private session between psychiatrist and artist, with the scientific gaze and the philosopher’s insights informing—or, more often, pitted against—one another. And in 1936, Antonin Artaud, having already cut himself loose from the strictures of Breton’s Surrealist movement and the precepts of scientific materialism, abandoned the Old World for the New and the narcotics of western pharmacy for the ancient sacrament of the cactus, and launched himself into a self-experiment without limits.

Sartre was injected with mescaline by his old school friend, the psychiatrist Daniel Lagache, at Sainte-Anne Hospital in Paris in January 1935 in the course of his researches into phenomenology, Edmund Husserl’s radically reconceived form of philosophy, which Sartre had encountered in 1933 and relocated to Berlin over that summer to study more deeply. Mescaline was a tool of obvious relevance to Husserl’s injunction that “a new way of looking at things is necessary.” Phenomenology aimed to describe reality purely as it was perceived, stripped of all theories, categories, and definitions: turning attention exclusively, in Husserl’s famous dictum, “to the things themselves.” Much of the mescaline literature to date, from the early peyote reportage of Silas Weir Mitchell and Havelock Ellis to the stream of consciousness dictated by Witkacy, had tended in this direction: in aiming simply to describe its visions and sensations without imposing definition or meaning on them, it had in a sense been phenomenology avant la lettre.

Sartre wrote little directly about his experience, describing it briefly in notes that later found a place in L’imaginaire, his 1940 study of the phenomenology of the imagination. He found its effects elusive and sinister. “It could only exist by stealth,” he wrote; it distorted every sensation, yet whenever he attempted to perceive it directly it withdrew into the background or shifted shape. Its action on the mind “inconsistent and mysterious,” offering no solid vantage point from which to observe it. In contrast to previous descriptions of the “double consciousness” or état mixte, in which the normal self was able to observe its hallucinations dispassionately, Sartre found it impossible to be a spectator of his own experience. On the contrary, he felt submerged against his will in a miasma of sensations that assailed him viscerally at every turn, a world of grotesque extreme close-ups in which everything disgusted him.

The best-known detail of Sartre’s bad trip is Simone de Beauvoir’s anecdote of him being haunted for weeks after by lobster-like creatures scuttling just beyond his field of vision. Sartre, like Aldous Huxley, was partially sighted—a curious coincidence linking two of the most celebrated intellectuals to have taken the vision-producing drug—and his poor vision may have exacerbated his anxieties about shapes lurking just beyond its reach. Later in life he claimed that it had driven him to a nervous breakdown. “After I took mescaline, I started seeing crabs around me all the time,” he recalled in 1971; “I mean they followed me into the street, into class.” Even though he knew they were imaginary he spoke to them, requesting them to be quiet during his lectures. Eventually he sought psychotherapeutic help from a young Jacques Lacan, which generated “nothing that he or I valued very much,” though “with the crabs, we sort of concluded that it was fear of becoming alone.”

“The crabs really began when my adolescence ended,” he added, raising the question of whether they were entirely the product of a mescaline trip at the age of thirty. They made a cameo appearance years later in his play The Condemned of Altona (1959), in which a race of monstrous crabs sits in judgment of future humanity. Mescaline is a less explicit but more pervasive influence on Nausea (1938), in which mundane objects continually reveal hideous aspects or dissolve into viscous masses, and a closer look at reality always risks an unwelcome surprise. In 1972, however, later in his series of conversations with the scholar John Gerassi, he recalled that “I liked mescaline a lot.” He recalled taking it in the Pyrenees: “As you know I am not a nature lover. I much prefer to sit four hours in a café”—but on mescaline the mountains “take on so many colors, it’s really art.”

Ten years after Sartre’s first experiment the phenomenologist Maurice Merleau-Ponty quoted some of his previously unpublished self-observations on the drug: “Everything seemed at once clammy and scaly, like some of the large serpents I have seen uncoiling themselves at Berlin zoo. Then I was seized with the fear of being on a small island surrounded by serpents.” Merleau-Ponty himself took mescaline in a dose much smaller than Sartre’s and found it more philosophically useful. He observed that hallucinations pose a particular problem for the scientific method, which tries to explain them as “an event in the chain of events running from the stimulus to the state of consciousness,” and thereby struggles to formulate their difference from reality.

Merleau-Ponty offered an alternative explanation, located not in brain activity but in the subject’s relations with the wider world. “When the victim of hallucination declares that he sees and hears” we cannot contradict him, but at the same time “we must not believe him,” since to call something a hallucination is also a statement that the sight and sound are not real. The phenomena are not purely intellectual: “All hallucination bears initially on one’s own body,” as a physical product of the senses. A hallucination is presented to the observer alone, and “the normal person does not find satisfaction in subjectivity … he is genuinely concerned with being in the world.” Hallucinogenic drugs such as mescaline show that perception and consciousness are more than private cerebral activities. They are irreducibly embodied and social.

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On May 22, 1934, eight months before Sartre’s experiment in Paris, the critic and philosopher Walter Benjamin was administered mescaline in Berlin, also via an old friend turned psychiatrist. Benjamin had known Ernst Joël since college days, after which Joël served as a doctor during World War I. On his return to Weimar Berlin, Joël turned to what he called “social psychiatry,” abandoning the world of private clinics and their wealthy clientele to practice among the poor in their homes. With his colleague Fritz Fränkel, Joël was conducting an extensive series of drug experiments that generated clinical papers on the psychology of addiction, a book on cocaine dependency, and a 1926 study of Der Haschischrausch.

The pair approached Benjamin, well known at this time as a newspaper columnist and public intellectual, as an experimental subject, first with hashish and later with mescaline. The sessions were nonclinical and loosely supervised: sometimes Benjamin was hosted in Joël’s Berlin apartment, at other times he wandered the streets and filed his report later. The mescaline session was supervised by Fritz Fränkel in Joël’s apartment and was largely unstructured, though Benjamin was presented with a few standard psychological tests. As was their protocol, doctor and subject filed parallel reports.

Benjamin’s interest in drugs developed early in his career, after he read Charles Baudelaire’s Les paradises artificiels; in 1919 he had written to a friend, “It will be necessary to repeat this attempt independently of this book.” The year 1927, when he first took hashish, was also the year he began his Arcades Project, a series of excursions and excavations into the Baudelairean street life of nineteenth-century Paris; it remained unfinished (as did the book about hashish itself that he decided to write in 1932). The many notes, text fragments, and experimental protocols that survive are a blurred composite of drug experiences and wanderings as a flaneur through cities past and present, real and imagined. His recollections of hashish and mescaline similarly blur into one another, and into the broader tapestry of his researches.

Throughout his writing on drugs Benjamin circled around the German term Rausch, usually rendered in English as “intoxication” but with deeper resonances: its underlying literal meaning of rush, roar, or thunder and, prominent for Benjamin, Nietzsche’s use of it to denote Dionysian ecstasy, the rending of the veil of appearances to reveal the primal life force. In its grip, as Benjamin wrote in his wanderings around Marseille on hashish, “images and chains of images, long-submerged memories appear”; the borders between subject and object weaken, imagination bleeds into reality, the world comes to life in new ways. It is not purely a dream or a fantasy but “a continual alternation of dreaming and waking states, a constant and finally exhausting oscillation between totally different worlds of consciousness.” “Intoxication” suggests a transient state of impairment, but Rausch describes an “ecstasy of trance” that holds out the possibility of reenchanting the world without demanding a romantic or religious leap of faith. It is not an effect of the drug per se but “a profane illumination, a materialistic, anthropological inspiration, to which hashish, opium or whatever else can give an introductory lesson.”

The mescaline experiment of 1934 began with Fränkel giving Benjamin an injection and then leaving the room. On his return a few minutes later, his subject seemed in a bad mood. He was irritable and fidgety, and described the onset of the drug’s symptoms as “an impertinence.” He complained that this was the wrong setting: the experiment should be taking place in a palm grove. He shivered, and in his own notes recorded: “In shuddering, the skin imitates the meshwork of a net. But the net is the world net: the whole universe is caught in it.”

When he closed his eyes he described not colored images but ornamental figures that he compared to those carved on Polynesian oars. He observed that the ornamental tendency could equally be applied to words, and doodled some repeated phrases in decorative shapes. When presented with Rorschach inkblots he complained—“the peevishness, the mood of discontent keeps returning,” noted Fränkel—before concentrating and tossing out a quick series of associations: two Siberian women, two poodles, a little woolen sheep, two embryos. He returned frequently to the subject of Nietzsche’s sister, Elisabeth Förster, and her attempts to control and pervert the meaning of her late brother’s archive. He announced several times that he had discovered the secret of Struwwelpeter, the nightmarish children’s book, but would not reveal it. Finally he pronounced: “A child must get presents, or else he will die or break into pieces or fly away, like the children in Struwwelpeter. That is the secret of Struwwelpeter.”

Benjamin’s elliptical notes on mescaline are similar in texture to his jottings on hashish, and not much different from those he habitually made while sober. His ambivalence is also characteristic. The sensation of Rausch was never for him entirely comfortable: it was a dialectic in which one had to guard against being swallowed by “the romantic turn of mind.” Like Sartre, part of him sought a detachment from the experience, while another part sought immersion. There was also a political dimension to consider: “The solitude of such intoxication has its dark side,” as he wrote elsewhere. In Berlin in 1934 there were good grounds for being suspicious of the surrender to the irrational. His nagging anxiety about the perversion of Nietzsche’s legacy by Nietzsche’s anti-Semitic sister perhaps reflects the intrusion of the political into Benjamin’s stream of thought.

Rausch was an awkward phenomenon in this context. To indulge in “hours of hashish eating, or opium smoking” was, from one angle, an act of escapism, a retreat from the communal, and a betrayal of political responsibilities. At the same time the 1929 Opium Law had made the drug-taker a criminal and, as the Third Reich tightened its grip, a degenerate and an enemy of society; this made drug-taking a form of private revolt and a potential tool of liberation. The relation between Rausch and rebellion was fraught and paradoxical, and perhaps a clue to Benjamin’s final insight about Struwwelpeter. Returning to his first reaction to mescaline at the end of his notes, he added: “Impertinence is the child’s chagrin at not being capable of magic.” This is why “a child must get presents”: it is too harsh to expect children to endure a life of struggle without some gratuitous gifts. In Rausch, as he wrote at the end of his evening on hashish in Marseille, “our existence runs through Nature’s fingers like gold coins that she cannot hold and lets fall so they can thus purchase new birth.”

Throughout his mescaline session Benjamin expressed to Fränkel his discontent with the drug, but at the same time complained he hadn’t been given enough. When he repeatedly refused to tell Fränkel his revelation about Struwwelpeter, the doctor speculated: “Punishment for the insufficient dosage.” In the final jotted phrases of his notes, Benjamin wrote, “Wisdom of impertinence.”

Mike Jay has written extensively on scientific and medical history. His books on the history of drugs include High Society: Mind‑Altering Drugs in History and Culture and The Atmosphere of Heaven. His work has been praised by Oliver Sacks, Richard Holmes, Jenny Uglow, and the New Scientist. He lives in London.

Excerpted from Mescaline: A Global History of the First Psychedelic, by Mike Jay, © 2019. Reprinted with permission from Yale University Press. All rights reserved.