If you’ve ever felt like your life is just a series of things happening to you rather than things you’re actually choosing, you’ve basically lived the plot of the Jean-Paul Sartre Age of Reason. It’s a book about being stuck. It is 1938 in Paris. The world is screaming toward a war that everyone knows is coming but no one wants to admit, and Mathieu Delarue—a philosophy teacher who should probably have his life together—is absolutely spiraling because his mistress is pregnant.
He doesn't want the kid. He doesn't really want the mistress, Marcelle, either. But he’s obsessed with this idea of "being free." He thinks freedom means having no ties, no debts, and no responsibilities. It’s a total mess. Honestly, it’s one of the most relatable "literary classics" ever written because it captures that specific, agonizing feeling of being an adult who still feels like a kid playing dress-up.
Sartre published this in 1945, right after the war ended, but he set it in that tense pre-war summer. It’s the first part of his Les Chemins de la liberté (The Roads to Freedom) trilogy. While people usually associate Sartre with dense, headache-inducing essays like Being and Nothingness, this novel is where the philosophy actually hits the pavement. It’s sweaty, anxious, and deeply human.
What Everyone Gets Wrong About Mathieu’s Freedom
Most people read the Jean-Paul Sartre Age of Reason and think Mathieu is the hero because he’s a philosopher. He isn't. He’s kind of a disaster.
His version of freedom is "freedom from" things. He wants to be free from the burden of a family. He wants to be free from the boring morality of the middle class. But Sartre is trying to show us that this is a hollow way to live. If you spend your whole life avoiding commitments just to keep your options open, you aren't actually free. You’re just empty. Mathieu spends the entire book trying to scrounge up 4,000 francs for an abortion, and in doing so, he betrays almost everyone he knows. He steals. He lies. He begs.
He thinks he’s being rational. He thinks he’s reaching the "age of reason."
The title is actually a massive piece of irony. In the French legal and social context of the time, the age of reason was when a person became responsible for their actions. Mathieu thinks he’s reached it because he’s cynical and detached. Sartre, however, is arguing the opposite: you haven't reached the age of reason until you realize that your choices define who you are, and you can’t escape that by just saying "I don't want to choose."
The Brunet Contrast: Action vs. Observation
Then you have Brunet. He’s Mathieu’s friend and a dedicated Communist. Brunet is the foil. He has "found" his freedom by committing to a cause. He tells Mathieu that his life is a void because he won't take a stand.
✨ Don't miss: 100 Biggest Cities in the US: Why the Map You Know is Wrong
Is Brunet right? Sorta. But Sartre is careful here. While Brunet has purpose, he’s also given up his individual thinking to the Party. Sartre is trapping the reader between two bad choices: Mathieu’s paralyzing indecision and Brunet’s rigid, almost robotic commitment. This tension is what makes the book feel so modern. We still do this today. We either scroll through life refusing to commit to anything, or we join an "online tribe" and let the group do our thinking for us.
The 4,000 Francs: A Study in Desperation
The plot is surprisingly tight for a "philosophical" novel. It’s basically a ticking clock. Marcelle is pregnant, and the window for a safe (though illegal) procedure is closing.
Mathieu’s journey through the streets of Paris is a tour of human failure. He goes to his brother, Jacques, who is a wealthy, boring lawyer. Jacques is actually one of the most interesting characters because he’s so "normal." He offers Mathieu the money on the condition that Mathieu marries Marcelle and lives a "respectable" life. Mathieu refuses. He’d rather be a thief than a husband. It’s a wild moment that makes you realize Mathieu’s "freedom" is actually just a very specific kind of selfishness.
Then there’s Daniel. Daniel is complicated. He’s a wealthy, self-loathing man who hides his sexuality and spends his time trying to find ways to punish himself. He eventually steps in to "help" Mathieu, but his motives are dark and twisted. He’s not doing it out of kindness; he’s doing it to spite Mathieu and to tie himself to a destiny he hates.
Why the "Age of Reason" Still Hits Different in 2026
You might wonder why a book about 1930s Paris matters now.
It matters because we are living in a massive "existentialist" moment. The Jean-Paul Sartre Age of Reason deals with the anxiety of choice. Today, we have more choices than any generation in history—where to live, what to work on, who to be—and yet, the depression rates are through the roof.
Sartre's point is that the "Age of Reason" is a myth we tell ourselves to feel safe. We think that eventually, we will become "adults" and everything will be clear. Mathieu realizes at the end of the book that there is no such thing as being "finished." You are always just the sum of your current actions.
🔗 Read more: Cooper City FL Zip Codes: What Moving Here Is Actually Like
"He was alone, free and alone, without help and without excuse, sentenced to decide without appeal, sentenced to liberty forever."
That’s the core of it. Freedom isn't a gift. It's a sentence.
The Aesthetics of Nausea and Smoke
Sartre’s writing style in this book is incredibly visceral. He doesn't just describe ideas; he describes the way a room smells or the way a drink tastes when you’re nervous. The characters are always smoking. Always drinking. Always looking at their own hands and feeling weirded out by the fact that they exist.
He uses a technique influenced by American novelists like John Dos Passos, where the narrative feels like a camera jumping from one person to another. This creates a sense of "simultaneity." You feel the whole city of Paris breathing and moving while Mathieu is having his private meltdown. It reminds us that our personal crises are happening inside a much larger, indifferent world.
The Role of Ivich and Boris
If Mathieu and Marcelle represent the "old" problems of adulthood, the siblings Ivich and Boris represent the terrifying vacuum of youth.
Boris is Mathieu’s student. He worships Mathieu but also thinks he’s an old man. Ivich is Boris’s sister, and Mathieu is weirdly obsessed with her. She’s impulsive, moody, and totally unpredictable. To Mathieu, she represents a "pure" kind of freedom because she acts on whims.
There’s a famous scene in a nightclub where Ivich cuts her hand with a knife just to see what happens, and Mathieu does the same. It’s a moment of blood brotherhood that is both pathetic and intense. He’s trying to catch some of her youthful fire because his own life feels like it’s turning into ash.
💡 You might also like: Why People That Died on Their Birthday Are More Common Than You Think
But Ivich doesn't want him. She doesn't want anyone. She is the embodiment of "nothingness." Watching Mathieu try to chase her while his actual life (Marcelle) is falling apart is a brutal look at how we use distractions to avoid our real problems.
Real-World Insights: How to Apply "Age of Reason" Thinking
If you want to actually get something out of this book besides a bleak mood, you have to look at the concept of "Bad Faith" (mauvaise foi).
Mathieu is the king of Bad Faith. He tells himself he can't marry Marcelle because it would ruin his freedom. He tells himself he has to get the money. He acts like his hands are tied.
In reality, his hands are never tied. He is choosing to be a person who steals. He is choosing to be a person who deserts his partner.
Practical Takeaways for Your Life
- Stop waiting for the "Right" Time: Mathieu thinks he’ll be ready for life later. There is no later. There is only what you are doing right now.
- Commitment is the only way to be free: This sounds like a paradox, but Sartre (and eventually Mathieu) realizes that if you don't choose something, you aren't free—you're just drifting. Choosing a path, even a hard one, is the only way to have an identity.
- Accountability is internal: You don't need a judge or a god to tell you you've messed up. You are your own witness. Mathieu’s "age of reason" is the moment he stops making excuses.
Final Perspective on Sartre’s Masterpiece
The Jean-Paul Sartre Age of Reason isn't a "fun" read in the traditional sense, but it is an essential one. It strips away the romantic lies we tell ourselves about our "potential" and forces us to look at our actual records.
Are you the person you say you are, or are you just a collection of things you've avoided doing?
The book ends with Mathieu alone, having "achieved" his goal of staying unattached, but feeling like a ghost. He has reached the age of reason, and it's much colder than he expected. It’s a cautionary tale for anyone who thinks that keeping your options open is the same thing as living.
To move from theory to practice, start by identifying one area of your life where you’ve been saying "I have no choice." Force yourself to rephrase it as "I am choosing to do X because I am afraid of Y." This simple linguistic shift is the start of the existentialist journey Mathieu was too scared to take until it was almost too late. Stop viewing freedom as the absence of weight and start viewing it as the strength to carry the weight you choose.