Peter Thiel, the billionaire technology investor and sometime Donald Trump adviser, has a cute line about death. “Basically, I’m against it,” he likes to say when the topic comes up. It comes up quite a bit, actually, because Thiel has spent millions of dollars of his personal fortune, and even more of his partners’ money, funding anti-aging research. In addition to backing numerous biotech startups working to extend human lifespans through his venture capital firm and his personal foundation, and taking human growth hormone to rejuvenate his own cells, Thiel has told me he is “very, very interested” in parabiosis, an anti-aging treatment that involves transfusions of younger people’s plasma. He employs a full-time medical consultant whose job is to research new health discoveries and report back.

Of course, who isn’t against death? Certainly not Thiel’s good friend and PayPal co-founder Max Levchin, who told me he’s hoping to cheat the reaper by uploading his consciousness into a supercomputer so that he’ll have an archived version to boot up once his body expires.

Not Sam Altman, the influential head of Y Combinator, who made a $10,000 refundable down payment to a company promising to euthanize him just before his natural death and flash-embalm his brain. (Altman tells me he paid the money primarily to support scientific advancement; by the time he has to worry seriously about aging, he expects humans and machines will have merged, rendering biology as we know it irrelevant.)

Google’s Ray Kurzweil is also fighting the fight. He takes 70 to 80 supplements every day to postpone his senescence for the 27 years he predicts it will take for computers to achieve runaway superintelligence and grant us eternal life (or, OK, snuff us out altogether).

So are Kurzweil’s bosses, Larry Page and Sergey Brin, who spun off a company, Calico, devoted to life-extending biology research; and Mark Zuckerberg, who launched a $3 billion initiative to cure all diseases this century; and Oracle founder Larry Ellison, who has bankrolled hundreds of millions of dollars’ worth of aging research; and the sundry other investors who like their chances of being the first human beings in history to escape the way of all flesh.

In Silicon Valley, going to extraordinary lengths to raise one’s life expectancy is like wearing FiveFinger shoes to work or microdosing LSD during a hackathon: a quirk that barely registers as a quirk.

But in the past few years, the epicenter of death defiance has changed. Even as entrepreneurs, thought leaders, and billionaires invest their time, bodies and fortunes in the project of cheating death, they’re also increasingly finding solace in something else: an ancient Greek intellectual tradition that views the natural rhythms of the life cycle—which is to say, dying—as a central fact of being. Which, most would argue, it is.

Stoicism emerged in the third century B.C. in the works of the philosopher Zeno of Citium, who influenced successors like Seneca, Epictetus, and the emperor Marcus Aurelius with his teachings about virtue and equanimity in the face of suffering. Its current vogue owes much to the imprimatur of the Valley’s own philosopher king, 4-Hour Workweek author Tim Ferriss, who championed a book about Stoicism, The Obstacle Is the Way, by marketing savant Ryan Holiday, and made it a must-read among lifehack fetishists.

Since then, the fad has taken on a life of its own. Susan Fowler, the Uber engineer whose blog post about sexual harassment touched off a chain of events that culminated in the resignation of CEO Travis Kalanick, said Stoicism emboldened her to speak out. Y Combinator put A Guide to the Good Life: The Ancient Art of Stoic Joy by William B. Irvine on a reading list for entrepreneurs, alongside books about the founding of Bell Labs, Nike, and Pixar. A rare rave from Recode editor Kara Swisher helped popularize an app called WeCroak, which sends users push notifications featuring Stoicism-flavored meditations.

Inevitably, many of these neo-Stoics are the same people who think the natural human lifespan is just another challenge to overcome, which is awkward, because if there’s one thing the Stoics were crystal-clear on, it’s that death is something not to avoid but to accept and even welcome. “The man who fears death will never do anything worthy of a man who is alive,” as Seneca put it.

“The Stoics are really about a kind of letting go,” says Nancy Sherman, a professor of classics and philosophy at Georgetown and author of Stoic Warriors: The Ancient Philosophy Behind the Military Mind. In the Stoic ideal, a wise person is one who seeks only to be virtuous, since virtue doesn’t require health, wealth, or anything else contingent on luck or circumstance. “When you start talking about ‘How long am I going to live?’ and ‘Am I going to be in the first cohort of immortal folks?’ it starts sounding like you’re messing with the wrong stuff,” Sherman says.

“The Stoics probably talk about death and the inevitability of death more than just about any other topic,” Ryan Holiday says. Stoics not only accept the reality of death; they force themselves to confront it at every turn, meditating on it in a practice termed memento mori. “Cicero said to philosophize is to learn how to die.”

Bill Irvine, a professor of philosophy at Wright State University in Dayton, Ohio, has been surprised to watch his book become a touchstone for a generation of entrepreneurs. “When I hear the directions they want to head, it dawns on me that they have a different understanding of Stoicism than I do,” he says. “It sounds to me like they’ve accepted some aspects of Stoicism, but then other aspects they choose to ignore. For instance, this thing of not clinging to life.”

Like the math that limits how many bitcoins can be mined — to use an analogy many born-again Stoics would appreciate — life’s finitude is what makes it feel precious. “Anything you have an infinite supply of is going to be wasted,” Irvine says. “In fact, if you say that there is a heaven and therefore a kind of immortality, a Stoic is going to be suspicious even of that.”

Contrary to the casual usage of the term to mean patient suffering, Stoicism was intended to be a strategy for finding satisfaction and meaning in life by distinguishing between the things that cause suffering, which we may be powerless to change, and the suffering itself, which is often a product of expectation or ego. As Epictetus put it, “The chief task in life is simply this: to identify and separate matters so that I can say clearly to myself which are externals not under my control, and which have to do with the choices I actually control.” Foremost among the externals is when and how life ends, and not just one’s own life, but also the lives of friends and loved ones.

“Stoics accept death,” Irvine says flatly. “For them, it’s going to happen. I’m not at all convinced that they would have thought overcoming it was a wise thing to even strive for.”

Fowler, the software engineer who used to work at Uber, has a theory about the popularity of the philosophy among transhumanists and lifehackers. “It’s peddled as a ‘lifehack’ out here (gross),” she emails. “It has been trendy, largely, I suspect, because people take away from it the idea of ‘Who cares what other people think? It’s all about me and my control over things.’” Fowler points to Seneca’s text The Shortness of Life as evidence that “if they were real Stoics, they wouldn’t be into the longevity stuff.”

Irvine thinks it’s about the love of the hack. Compared with something like Buddhism, which can take decades to understand and master, the basic tenets of Stoicism are relatively easy to learn, and the potential benefit — less suffering — seems to be a state worth striving for. “You can try it this weekend and you’ll know whether or not it’s working for you,” he says. “If you’ve got a very practical-minded, rational person who wants a solution that works now and not in 20 years, Stoicism is very good for that.”

That’s how Geoffrey Woo sees it. Woo is the founder of HVMN, which makes supplements that aim to enhance mental and physical performance. He’s an influential figure in San Francisco’s biohacking community, leading a weekly intermittent-fasting meetup that draws hundreds of attendees. (Among the benefits attributed to intermittent fasting are longevity-enhancing changes in gene expression and mitochondrial activity.)

In Stoic teachings on death, such as Marcus Aurelius’ exhortation to “execute every act of life as though it were your last,” Woo sees a parallel to Steve Jobs’ oft-quoted 2005 commencement address. In that speech, the Apple co-founder, already sick with the pancreatic cancer that would kill him, praised death as “the single best invention of life” and exhorted his audience, “Your time is limited, so don’t waste it living someone else’s life.”

Thinking in those terms “is a very good heuristic for making life decisions,” says Woo, likening it to the “regret minimization framework” used by Amazon’s Jeff Bezos. “It’s a way to have a short-term focus, a clarity of vision of what you want to do now while preserving the optionality of having more time.”

When I interviewed Thiel in 2015, he also brought up Jobs’ speech, but only to challenge its assertion that mortality is motivational. “I believe the exact opposite of that,” Thiel said. It’s the imminence of death, not obliviousness to it, that encourages complacency, he argued. He brought up a grand-uncle who, at 85, had said he would have gotten a few more PhDs if he’d known he would live so long. “Maybe it’s when people think they have no time left that they don’t undertake things.”

Whichever argument you find more persuasive, it’s noteworthy that both couch the idea of making the most of one’s time on earth, whether by getting more out of each day or by getting more days. In Silicon Valley’s cult of productivity, historically spiritual practices such as meditation, fasting, and psychedelic drug use have all been pressed into the service of crushing it at work. Philosophy is just one more time-management technique, like the Pomodoro time-management method or drinking Soylent at your standing desk.

Dave Asprey, a tech investor turned Bulletproof biohacking guru, is a Stoicism proponent who has hacked the hack. Rather than rely on meditation to help him overcome his hangups about mortality, Asprey spent four months of his life taping electrodes to his skull and sealing himself in a neurofeedback chamber, where he systematically deleted his brain’s instinctive responses to thoughts of death and other stimuli.

“I went through all the fears I could think of and programmatically eliminated them,” Asprey, author of the upcoming book Game Changers, told me. “And I think it works because I’m writing a substantial book every year, my podcast is crossing 100 million downloads, I’m CEO of a venture-backed company with $50 million in funding, I’m a dad, and I’m not even stressed out.”

Asprey, who is 44, doesn’t plan to live forever, but he does intend to enjoy the equivalent of two long lives, maybe more. “My perspective is I’m absolutely comfortable with the fact that I’m going to die, if nothing else than because the universe is going to die at some point,” he says. “I would like to die at a time and by a method of my choice.” Asprey thinks his peers who seek true eternal life could benefit from his neurofeedback exercise — not so much spiritually but from a health standpoint, since stress accelerates aging. “I call them the fearful immortalists. Living in a state of terror is a sure way to make sure you die more quickly.”

Asprey is also big on the health benefits of gratitude and says securing extra time on earth is a matter not just of productivity but of giving back. “I’m trying to live long because I have a lot of important things to do, things I think are meaningful. And they’re not for me. They’re for others.”

Conceiving of one’s own survival as an act of altruism may square the circle of Stoicism and life extension: Since Stoics care only about virtue, then as long as you’re engaged in virtuous acts, you can wrap your continued existence in the mantle of Stoicism.

But thinking about life as a vessel for future achievement negates many of Stoicism’s benefits, says Hansa Bergwall, creator of WeCroak. For 99 cents, WeCroak sends its users five philosophical or religious meditations per day that arrive via a push notifications that read, “Don’t forget, you’re going to die.” The strivers who think it’s an alarm clock reminding them to get hustling already are missing the point, Bergwall says. “There’s a way in which we overemphasize ambition at the cost of a really rich, soulful life,” he says.

Bergwall’s inspiration is his father, who co-founded the first tofu company in America. After 15 years of working nights and weekends, Bob Bergwall sold the company for a fortune, only to lose his wife, Hansa’s mother, to a brain aneurysm a year later. “So all those cruises, all those vacations, all those things he wanted to do together, he didn’t get to have much of it,” Bergwall says. “If he could have lived differently, he would have chosen a more balanced life.” For his part, Bergwall considers the pursuit of immortality pure folly.

“The truth about death isn’t going to change,” he says, “and you need to keep that truth close in order to live in accordance with our nature.”

Yet Bergwall’s assertion that the truth about death isn’t going to change is exactly what’s in contention. It’s not hard to find real scientists who talk about the development of new medical treatments leading to “escape velocity,” the point at which human life expectancy will begin increasing by more than a year for every calendar year that passes. (It’s the gerontology version of the Singularity.)

“Obviously if you were around when Marcus Aurelius was around and your goal was to achieve escape velocity, that would be unhealthy,” says Nikhil Suresh, a graduate student studying data science at Monash University in Australia who credits Stoic texts for getting him through hard times. “It says something when someone contemplates it now; they can’t just be dismissed as crazy. The fundamental problem we’ve had throughout all of human existence is we simply don’t have the capacity to tackle death, so we make our plans as though death is on the way.”

Indeed, there’s a case to be made that the Stoic’s teachings will only become more necessary should something like escape velocity come to pass. For all Silicon Valley’s optimism, there’s little reason to think our relationship to mortality would be less tortured if living to 200 or 500 or 1,000 were the norm. Maybe we would be paralyzed by existential dread, afraid to leave our beds — much less undertake acts of bravery and altruism — for fear of a patch of black ice or a misprogrammed autonomous vehicle. Maybe our personalities would fray and unravel from too many centuries of change, we’d be bored out of our minds, or we’d simply sink into apathy, content to put off until the next millennium what we could do today. “Choose to die well while you can; wait too long and it might become impossible,” wrote Gaius Musonius Rufus. Immortality might just make Stoics of us all.