Simone de Beauvoir, the influential feminist and existentialist philosopher, was a serious hiker.

Simone de Beauvoir's 'The Second Sex' merged existentialism with feminism

De Beauvoir’s 1949 philosophical treatise criticized patriarchy and its negative impact on women. She argued that gender differences were mainly due to socialization rather than innate qualities, writing that “one is not born, but rather becomes, a woman.” In turn, de Beauvoir believed women should refuse predetermined gender roles and instead define themselves, echoing a key tenet of existentialism.

Simone de Beauvoir's lone play has mostly been overlooked

Although primarily known as a philosopher, Beauvoir wrote the play "The Useless Mouths," which debuted in Paris in November 1945. The work is about a government allowing "useless" citizens—women, children, the elderly—to starve during a food shortage. While it's not widely staged, some Beauvoir scholars believe it's a significant text that explores many of the existential themes she explores in her other work.

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."

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.

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 Vatican included 'The Second Sex' on its list of forbidden books

In 1956, the Vatican added Simone de Beauvoir's "The Second Sex" and her novel "The Mandarins" to its Index Librorum Prohibitorum, which already included every book by her partner Jean-Paul Sartre. The Vatican newspaper explained that de Beauvoir's books, which advocated for birth control and criticized marriage, included "the harmful atmosphere of a certain existentialist philosophy" that contained a "hidden poison." (Some readers may experience a paywall.)

Many writers considered 'existentialist' didn't identify with the term

“Existentialism” was first introduced in 1943 by philosopher Gabriel Marcel. Jean-Paul Sartre and Simone de Beauvoir readily adopted the term, but others, such as Albert Camus and Martin Heidegger, rejected it. Earlier philosophers, like Søren Kierkegaard and Friedrich Nietzsche, were long dead by the time the word was in vogue.

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.

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

Novelist Richard Wright joined the existentialists in Paris

The author of “Black Boy” and “Native Son” left the United States in 1946 to escape his home country’s racial inequality. In Paris, he explored existentialist ideas and spent time with Simone de Beauvoir and Jean-Paul Sartre. “The Outsider,” a novel he wrote while living in France, embraced many of the philosophy’s central themes.

'When you're climbing Mount Everest, nothing is easy. You just take one step at a time, never look back and always keep your eyes glued to the top.'

- Author Jacqueline Susann (1918-1974)

An existentialist reading list

If you’re looking for a starting point for diving into existentialist thought, this is a great resource. Its titles are not exactly obscure—Albert Camus’ “The Stranger,” Franz Kafka’s “The Trial,” and Søren Kierkegaard’s “Either/Or” are among the most famous works in Western literature—but the list provides some digestible context for each text, which will help you decide the best place to begin your journey.

'I always like to fake bravery. But I really think that solidified me being brave, speaking up for myself and just putting myself first.'

- Seven-time Olympic gold medalist Simone Biles (1997-present)

Existentialism is a loosely defined philosophy that encouraged authentic living

The writers and thinkers often characterized as “existentialist” sometimes contradict one another. Considering that, boiling the philosophy down to a set of tenets can be difficult. Generally, those associated with existentialism were inspired by the 19th-century works of Søren Kierkegaard and Friedrich Nietzsche, and they believed that individuals needed to defy conformity and define the meaning of life for themselves.

Existentialism inspired Franklin Roosevelt and Martin Luther King Jr.

The Danish philosopher, sometimes called “the father of existentialism,” believed that individuals needed to resist the temptation of conformity and instead discover their authentic selves. His work became remarkably influential in the 20th century. In 1944, Roosevelt said that reading Kierkegaard made him understand how the Nazis could’ve enacted so much violence. In 1959, King wrote that existentialism was “especially meaningful for our time.”

Joan Didion's 1967 'Slouching Towards Bethlehem' laid the hippie counterculture bare

Didion wrote a detailed account of living alongside hippies in San Francisco's Haight Ashbury area in the 1960s. Beyond their style and politics, Didion uncovered chaos, with one particularly shocking interview of a 5-year-old on LSD. Her stories challenged the movement's message of freedom and utopia in California.

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.

'I am a writer who came from a sheltered life. A sheltered life can be a daring life as well. For all serious daring starts from within.'

- American novelist Eudora Welty (1909-2001)

Albert Camus' 'The Fall' encourages readers to live without illusions

The writer's final complete novel is a series of dramatic monologues from Jean-Baptiste Clamence, who tries to explain to a stranger the sound of laughter that began following him. As the "Philosophize This!" podcast argues, the book is Camus' attempt at wrestling with some of the thornier aspects of existentialism in a form that's more digestible than a dense philosophical tome.

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.

One teacher's lesson on existentialism and social media use

During a unit on existentialist literature and philosophy, one teacher at Massachusetts’ Phillips Academy asked students to surrender their cell phones to test Kierkegaard’s thoughts on the danger of conformity and Sartre’s belief that humans are “condemned to be free.” Many of them were surprised to find how liberated they felt once they left behind social media.

Sartre and de Beauvoir's literary journal was named after a Charlie Chaplin movie

The couple founded the magazine Les Temps Modernes in 1945 and it quickly became essential reading for French intellectuals. Its name came from "Modern Times," Charlie Chaplin's 1936 movie that satirized the industrial revolution's dehumanizing effects.

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.

Scholars trace existential anxiety back to early Hebrew scriptures

Paul Megna, a scholar of literature and philosophy, notes that the existentialist ideas of Kierkegaard (and, to a lesser extent, Sarte and Camus) had their roots in much earlier texts, which posited that "fear of the Lord" was "the beginning of wisdom."

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

In 1935, Sartre was injected with mescaline, a psychedelic drug that was then used to treat alcoholism and depression, by his friend at the Hôpital Sainte-Anne in Paris. It was not a good trip: Sartre saw nightmarish crabs for days and suffered a mental breakdown. For the rest of his life, crustaceans like the ones he saw during the hallucination appeared in his works.

How yoga philosophy inspired Thoreau

In the 19th century, yogis traveling in America emphasized the practice as a philosophical one rather than a purely physical act. Like many Americans at the time, including his friend Ralph Waldo Emerson, Thoreau was intrigued by yoga's mysticism, once writing, "I cannot read a single word of the Hindoos without being elevated."

'Getting old is like climbing a mountain; you get a little out of breath, but the view is much better!'

- Actress Ingrid Bergman (1915-1982)

Why one runner believes Stoic philosophy is important for marathoners

There's plenty of time for thinking while training for a marathon, and Matt Fitzgerald suggests it'd be wise to study the Stoic philosophers to navigate the many frustrations that come with that training. Fitzgerald may be talking about running, but his advice can apply to any seemingly impossible goal.

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.

'Her own thoughts and reflections were habitually her best companions.'

- Legendary author Jane Austen (1775 -1817)

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.

'It might be that some day I shall be drowned by the sea, or die of pneumonia from sleeping out at night, or be robbed and strangled by strangers. These things happen. Even so, I shall be ahead because of trusting the beach, the night and strangers.'

-Janet Reno, the US' first female attorney general (1938-2016)

Ten writers and thinkers on what growing older actually requires of us

The Marginalian's Maria Popova curates a collection arguing our culture has learned to dread aging while forgetting it is a privilege, and that the antidote is sustaining passions strong enough to keep us from turning inward. Voices include Simone de Beauvoir, Joan Didion, Pablo Casals, and Kahlil Gibran.

A comprehensive biography of Emily Dickinson, the influential American poet

This deep dive into Dickinson's biography includes a fascinating anecdote about her time at Mount Holyoke Female Seminary—where she was distinguished from the "established Christians" and deemed "without hope"—as well as the significance of her correspondence with close friend Susan Gilbert, one of her primary readers and eventual sister-in-law.

'Wanderer Above the Sea of Fog' is an iconic romantic artwork

Caspar David Friedrich’s painting portrays man’s fascination with the natural world and emphasizes his smallness in the midst of its grandeur, epitomizing Edmund Burke's concept of "the sublime."

Romantics sought to experience 'the sublime'

“Sublime” may be a word that’s still used in popular culture, but when Irish philosopher Edmund Burke used it in a 1757 essay, he was attempting to define an astonishment at something that was beyond full human understanding.