A mescaline-induced hallucination stayed with Jean-Paul Sartre throughout his life

Jean-Paul Sartre was amazed by American jazz

The French philosopher wrote about a 1947 trip to a New York jazz club as a transcendent experience, describing the magic of the relationship between performer and audience: "You shout, they shriek, they whistle, they are possessed, you are possessed."

In 1951, a small French town was likely overtaken by the fungus that ultimately led to LSD.

Sartre spent his time in the French Army working on a novel

The writer's physical limitations (including partial blindness and balance issues) prohibited him from serving on the front lines. Instead, he worked as a military meteorologist. The job was not very demanding, so he spent most of his time writing. He told Simone de Beauvoir it was "extremely peaceful work; indeed I cannot think of any branch of the services that has a quieter, more poetic job."

The FBI kept tabs on Camus and Sartre

Jean-Paul Sartre worked as an American correspondent for Combat, the newspaper edited by Albert Camus. While he was in the States, J. Edgar Hoover's FBI kept tabs on him, concerned that Combat was publishing unfavorable portrayals of the US.

Philosopher and playwright Jean-Paul Sartre staged his first play while he was imprisoned in a POW camp.

Camus and Sartre admired each other's work before becoming friends

The two writers, who would later be considered two of the biggest names associated with existentialism, wrote positive reviews of each others' early work, with Camus praising Sartre's novel "Nausea" and story collection "The Wall" and, later, Sartre favorably compared Camus' "The Stranger" to Franz Kafka and Ernest Hemingway. Still, their reviews included some critiques, hinting at the larger disagreements that would come much later.

Sartre eventually denounced communism

The French philosopher was a long-time ardent supporter of communism and the USSR. He finally spoke out against the movement with the 1956 Soviet invasion of Hungary, saying that the move was "made possible by 12 years of terror and imbecility."

Sartre admired American novelist William Faulkner

In addition to writing philosophy and fiction, Jean-Paul Sartre was also a literary critic. His 1939 essay on Faulkner's "The Sound and the Fury" focused on the way the American novelist commented on time, favorably comparing him to Marcel Proust. Ultimately, Sartre argues Faulkner's "despair" about a "closed future" is a result of the "social conditions of our present life." Ever the existentialist, though, Sartre suggests this reality is something that should inspire rather than depress.

Sartre was an elaborate prankster as a student

After Charles Lindbergh completed his first solo transatlantic voyage in 1927, the French philosopher—then a student at Paris' École normale supérieure—called various newspapers to tell them the American pilot would be granted an honorary degree. Over 500 people showed up to find a Lindbergh lookalike Sartre had hired. "The public fell for it, and an old man even kissed his hand," Sartre later wrote.

Sartre's 1980 funeral attracted a massive crowd

The legendary existentialist died April 15, 1980. A week later, mourners packed the streets of Paris to pay tribute. Estimates suggest that between 20,000 and 50,000 people were in attendance. In the Associated Press footage below, you can watch them following the hearse from the hospital where the thinker died to his resting place in Montparnasse Cemetery.

Jean-Paul Sartre worked on 'Being and Nothingness' while a prisoner of war

The Nazis invaded France in May 1940. Sartre, as a member of the French Army, was taken prisoner that June. While he was in captivity, he studied Martin Heidegger and worked on "Being and Nothingness," one of his most famous philosophical works.

Jean-Paul Sartre believed 'existence precedes essence'

The existentialist figurehead argued that humans are not born with an identity or purpose; instead, they develop them throughout their lives. For Sartre, this meant making meaning for oneself rather than relying on authorities (like religion or government) to provide it.

Sartre and de Beauvoir had an open romantic relationship

The two figureheads of existentialist thought were romantic partners, though they had a publicly open relationship and never lived together. As de Beauvoir says in the interview below, "third persons knew our relationship dwarfed any we could have with them."

Psychedelic side effects, including worsening mental health for some patients, give pause

This article explores whether the therapeutic potential of psychedelic drug use is really as good as current research suggests. Scientists are exploring its applications for conditions ranging from the existential crisis that can accompany terminal diagnoses to chronic mental health conditions, including anxiety and PTSD.

Sartre wrote an 8-hour screenplay for a Freud biopic

Sartre was hired to write the screenplay for what would eventually become John Huston's 1962 film "Freud: The Secret Passion," about the life of the psychoanalyst. Sartre, however, had trouble sticking to the parameters of Hollywood. An early draft was estimated to be five hours long. Rather than shortening it, as Huston suggested, Sartre extended it to eight hours and was eventually removed from the production.

Sartre panned 'Citizen Kane'

Jean-Paul Sartre was primarily known for his philosophy, fiction, and drama, but he was also a critic. In 1945, he wrote a rather negative review of Orson Welles' "Citizen Kane," deriding Welles' decision to tell the story in the past tense, writing, "film in the past tense is the antithesis of cinema. Therefore 'Citizen Kane' is not cinema."

Camus directed a Picasso-penned play

The show, called "Desire Caught by the Tail," was written by Picasso in 1941 while living in Nazi-occupied Paris. It was first staged in 1944, featuring several French intellectuals, including Albert Camus, who directed, as well as Jean-Paul Sartre and Simone de Beauvoir, who had starring roles.

One of Sartre and de Beauvoir's lovers accused them of exploitation

The philosophical duo's open relationship sometimes included shared partners, including de Beauvoir's students. One of those students, Bianca Lamblin, wrote a book, "A Disgraceful Affair," about the experience and characterized it as sexual exploitation.

LSD fueled a countercultural movement before evolving into a potential therapeutic

As the use of recreational psychedelics became common, authorities were quick to claim LSD had lasting adverse effects, criminalizing the drug and halting scientific study for decades. Over time, LSD's reputation shifted from a potential source of enlightenment to a dangerous drug that could dim a person's future, and back to a possible therapeutic compound.

JJ Schildkraut theorized depression is linked to brain chemical imbalances—in 1965

Schildkraut was one of the first to put forward this idea, which stemmed from lab animal research. A decade later, researchers published the first landmark paper on fluoxetine—better known by trade name Prozac—which increases serotonin levels in the brain.

Jean-Paul Sartre rejected his Nobel Prize for literature

Sartre won the award in 1964, but refused it, explaining, "The writer must therefore refuse to let himself be transformed into an institution, even if this occurs under the most honorable circumstances, as in the present case."

Camus and Sartre had a public falling out over communism

The two were close friends, sometimes collaborating throughout the 1940s, but the release of Camus' 1951 book, "The Rebel," led to a schism over differing views on communism.

A psychedelic hamburger led one member of the Manson Family, the murderous cult led by Charles Manson, to testify against the group's leader.

'Brave New World' author Aldous Huxley turned to LSD on his deathbed

As "Brave New World" author Aldous Huxley lay dying of cancer in 1963, he asked his wife Laura to dose him with the hallucinogen LSD. A month later, Laura Huxley wrote a letter detailing the author's final trip, which she notes ended "so slowly, so gently, like a piece of music just finishing in a sempre piu piano dolcemente."

Mental health applications of psychedelics

Scientists are investigating psilocybin, ketamine, LSD, and MDMA (also known as ecstasy) as potential treatments for mental health issues. These drugs enable an altered state of consciousness, which can have beneficial or harmful impacts depending on the nature of the experience. Research suggests these drugs can be effective in treating substance use disorders, mental health conditions, including depression and anxiety, and psychiatric disorders, including schizophrenia.

Historians theorize Vincent Van Gogh suffered from Ménière's disease or epilepsy

A century after researchers suggested he suffered from epilepsy, some researchers in the 1990s began to support an alternate diagnosis: Ménière's disease, since he had suffered from severe, repeated attacks of disabling vertigo. Still, some researchers remain skeptical of the Ménière's diagnosis. One posits that Van Gogh had temporal epilepsy complicated by his absinthe consumption.

Existentialism has been used as a therapeutic tool, with 2 Swiss psychiatrists pioneering the philosophy's concepts to help patients navigate their issues.

Using psychedelics to manage a cancer diagnosis

Dr. Roland Griffiths helped lead the revival of psychedelic research, often prescribing the use of psilocybin to address severe depression or anxiety in patients. This podcast explores how Griffiths leaned on his own career after being diagnosed with cancer and facing the prospect of death.

LSD was discovered accidentally after its inventor touched his face and hallucinated.

Camus contracted tuberculosis as a teenager

There was still little understanding of treatment for the disease at the time; for most people, a tuberculosis diagnosis was a death sentence. The 17-year-old Camus was quarantined in his uncle's house, where he grew into an avid reader. Scholars note that the experience would inform his later work, including his 1947 novel "The Plague."

Sartre believed those who deny their own freedom are operating in 'bad faith'

In "Existentialism is a Humanism," Sartre argues that humans are "condemned to be free"—they are not confined to a divine fate, which means they must take the responsibility of creating their own destinies. Those who reject this freedom, by his estimation, are living in "bad faith."

In 1957, a vice president at JPMorgan became an outspoken evangelist for psychedelic mushrooms.

Existentialist literature explores the philosophy's ideas

Existentialism isn't confined to philosophical texts. Some of the movement's figureheads, like Albert Camus and Jean-Paul Sartre, were also novelists. Christina Howells, Professor of French at the University of Oxford, suggests this is because existentialism, as a philosophy, requires human stories to be fully understood, and literature makes the experience of the human condition more present and immediate.

Read Albert Camus' 'Myth of Sisyphus and Other Essays'

Camus' most famous work of nonfiction is this collection of philosophical essays. Perhaps the most resonant entry is the title essay, which reimagines the Greek myth of a man condemned to roll a boulder for all eternity. Rather than presenting the story as a cautionary tale about defying the gods, as the original myth intended, Camus considered Sisyphus an "absurd hero" for his actions and imagined him smiling as he endlessly toiled at his repetitive punishment.

Jean-Paul Sartre famously wrote that 'Hell is—other people'

The line appears toward the end of the play "No Exit." One character, realizing that he's confined to live out the rest of his days with the play's other two characters, exclaims, "There's no need for red-hot pokers. Hell is—other people!"

Pablo Picasso's Blue Period, one of his most recognizable artistic eras, was inspired by the loss of his friend, Carles Casagemas.

Psychedelics interact with neurotransmitter systems to alter one's perception

LSD, psilocybin, and MDMA can suppress the brain's default mode network and enhance connectivity. Research shows that, when paired with therapy, psychedelics may help treat mental health conditions, including depression, addiction, and PTSD.

Widespread use of LSD sparked a counter-cultural artistic movement in the 1960s

The trippy visuals often associated with LSD flourished in the 1960s as the drug became more widespread. Psychedelic design, defined by its undulating text and graphics, ultimately grew beyond just visuals, spawning psychedelia, a term that includes art, music, and cultural experiences based on psychedelic experiences.