Stoicism is having a moment. It’s always been popular in certain circles, for example as a buttress against chaos for military men. U.S. Admiral James Stockdale famously used the Stoic counsel of the ancient sage Epictetus to steady his mind as a prisoner of war in Vietnam. But recently Stoicism has gone mainstream in less dramatic scenarios as well. It’s a major source of inspiration for Cognitive Behavioral Therapy (CBT), an appealingly sensible form of professional counseling that eschews Freudian navel-gazing in favor of actionable mental discipline. In the 2010s, marquee titles like Ryan Holiday’s The Obstacle Is the Way (2014), named after a famous aphorism from Emperor Marcus Aurelius’ Meditations, helped establish a cottage industry of influencers who offer digestible neo-Stoic rules for life. Donald J. Robertson, a cognitive behavioral therapist and a well-respected popularizer of Stoic teaching, is part of this trend. His new biography, Marcus Aurelius: The Stoic Emperor, is a readable introduction to the ancient world’s most celebrated philosopher-king.

Stoicism’s most effective ideas are timeless: focus on what you can change, accept what you can’t. Cultivate a habit of thinking through your emotions before acting on them. These kinds of practices have always enjoyed some degree of popular appeal, ever since they were pioneered by Zeno of Citium at the turn of the 3rd century B.C. At that point, in Athens, philosophy was evolving from an offbeat subculture into a public-facing lifestyle market. Gone were the days when Bohemian eccentrics like Socrates could simply throw together ad hoc seminars at exclusive drinking parties. In the Hellenistic Era (323-30 B.C.) a wise man in search of followers had to establish a scholē—a “school.” That word, which had once referred casually to the leisure pursuits of the monied classes, was now coming to mean something much more formalized and systematic: a comprehensive training program with dedicated postulants learning to live by set principles. Most schools derived their teachings from a unified field theory of life, the universe, and everything, organized into three interrelated disciplines: ethics, physics, and logic. This was, in effect, the era when “schools of thought” were invented. They immediately entered into competition with one another—and the Stoics were hugely successful competitors.

Unlike their major rivals, the Epicureans, they had few reservations about full-bore engagement in the affairs of public life. Unlike their more aggressively countercultural predecessors, the Cynics, they didn’t make a show of bucking convention or pride themselves on antisocial behavior. And their most distinctive moral proposition was also their most expansive recruitment pitch. In all three of the key subjects, the Stoics emphasized unity: logic, physics, and ethics alike were governed by a single logos or rational order that pervaded the entirety of existence. And so, in the days of many gods, the Stoics teetered on the verge of monotheism. The logos was synonymous with the mind of Zeus, who governed all things and might even be the only real deity, the others being merely avatars or emanations of his nature. As a result, the signal fact to keep in mind about ethics was the descent of all humanity from one heavenly father: even slaves, wrote the Roman Stoic Seneca, are “sprung from the same stock” as their masters, “smiled upon by the same sky.” Whereas many pagans took it for granted that some are born booted and spurred, the Stoics—echoing the Jews and anticipating the Christians—taught that differences of status and title had no bearing on the human potential for wisdom, which alone could confer true freedom of heart and mind.

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Those more interested in practicalities than in metaphysics have always been tempted to lift Stoicism’s appealing moral principles out of the system and use them as a form of self-help, leaving the rest in a conveniently hazy background. That is effectively what modern life coaches do, but they were anticipated in the habit by the pragmatic Romans, whose men of action tended to favor Stoicism among the Greek schools. It is ethics above all that makes Stoicism so hugely scalable. Well into the heyday of the Roman Empire, it was preached and practiced by disciples all across the social hierarchy—from slaves like Epictetus to sovereigns like Marcus Aurelius.

Aurelius was not Stoicism’s most dazzling abstract thinker, but he was probably its most impressive practitioner. He certainly never expected or hoped to become its bestselling author. As Robertson points out, it’s ironic that Meditations has endured so long and circulated so widely, since it wasn’t really meant for public consumption. The book appears in Greek under the title ta eis heauton, “Notes to Himself.” If it sometimes comes across as repetitive, disjointed, or opaque, that’s because it’s basically a journal Aurelius kept while on campaign at the empire’s northeastern borders during the A.D. 170s, where he was busy skirmishing with rowdy barbarian tribes. But that’s what makes the book so inexhaustibly fresh and touching: Meditations is not a polished treatise by a self-appointed expert. It is an eminently relatable notebook, written on the fly in the midst of frustrations large and small. More than one entry is about the drudgery of getting up early: “At dawn, when you have a hard time getting out of bed, say to yourself…. ‘Is this what I was made for? To huddle under the covers and stay warm?’”

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Philosophers who know all the right answers are easy to come by, and tedious to read. Philosophers who have to buck themselves up in the morning are something altogether more special. Like Søren Kierkegaard or Ludwig Wittgenstein, Aurelius has the disarming virtue of being able to admit when he’s at a loss. Like his fellow Stoic Seneca the Younger, or even like Saint Paul, he frets over the difference between knowing what you should do, and getting yourself to do it. The Stoic life is simple but not easy: as Epictetus put it, “we have to make the best of whatever is in our power, and take everything else as it naturally happens.” It’s incalculably reassuring to learn from Aurelius that even great men have a hard time attaining that degree of resolve. Ever since the 17th century, when translations started appearing in Europe, modern readers have found Meditations and its author easy to love. Whether he quite meant to or not, Aurelius has invited the world into his private confidence.

He is only getting more popular. Unlike some other wisdom traditions, Stoicism has made the leap from print to digital media with notable success. On Reddit, the endless online labyrinth of discussion threads and trending topics, a forum devoted to practicing Stoicism called “r/Stoicism” has over 630,000 followers. It’s not hard to see why. Like a kind of Hellenistic era in hyperdrive, the internet age has played host to a swarm of conflicting ethical trends and life hacks, each vying for adoption by disoriented young seekers. The viral satirist Bo Burnham’s song “Welcome to the Internet” describes the whirligig array of lifestyle options that might flurry past a wandering scroller: “Here’s a healthy breakfast option, / You should kill your mom, / Here’s why women never f–k you, / Here’s how you can build a bomb.” In this deranged environment, Stoicism has emerged as a mercifully sane, decent, and time-tested way to manage anxiety and bring some desperately needed order to life. Digital technology has sifted through our store of cultural resources like a winnowing fan, leaving behind some surprising winners and losers. Stoicism is one of the winners.

Robertson’s own online presence embodies some of the level-headed clarity Stoicism is known for. He occasionally makes his views on current events known (he has some garden-variety criticisms of Donald Trump, for example), but mostly he stays away from politics and sticks to careful reading of ancient literature. It’s common to find users on r/Stoicism linking to Robertson’s Substack articles or asking him to help them check the sources for some Marcus-related post. (Did his wife really cheat on him with a gladiator? Probably not, Dr. Robertson argues, but the rumor is ancient.)

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Marcus Aurelius: The Stoic Emperor is the grown-up version of a graphic novel Robertson produced in 2022, Verissimus. The latter title refers to a nickname Marcus picked up at a tender age from one of his most important patrons, the emperor Hadrian. Hadrian was drawn to this somber young boy, left fatherless at the age of three or four by some catastrophe unknown to us. He must have been a magnetic character even then—solemn, precocious, eerily careful with his words. “Marcus’s family name Verus can mean ‘True,’” Robertson explains in the new biography; “Hadrian’s joke was that the boy’s name should be elevated to Verissimus, ‘Most True’ or ‘Truest,’ as if to say that he was the most honest and plainspoken person in Rome.” No one knows what Marcus said to Hadrian to earn the name; it must have been blunt enough to amuse his benefactor but cagey enough to avoid wounding the notoriously fragile imperial ego.

Whatever Marcus said, it was less than he felt. He never specified, even in his private notes, exactly what repelled him about his predecessor. Given the treacherous atmosphere of court intrigue that he had to move through, it was a prudent omission. But Hadrian is conspicuously absent from a list of Marcus’ role models in Meditations, which elsewhere lavishes praise on his adoptive father, the dutiful elder statesman Antoninus. It’s characteristic of Aurelius that he says everything he needs to about Hadrian by choosing when to keep quiet: “it creates the impression,” writes Robertson, “that Marcus had literally nothing good to say.”

Hadrian was preening and moody; by the end of his life he had sunk into a drawn-out fit of paranoid melodrama. He was also a lech when it came to the young boys in his retinue, one of whom—the ethereal and enigmatic Antinous—he venerated as a kind of divine consort. Sex between older men and young boys was normal within limits. But that probably didn’t make it any less scarring for the pre-teens involved, and Hadrian’s affairs had a sickly whiff of the decadent about them even for the time. Whether or not Marcus was an object of Hadrian’s more prurient interests, he seems to have come away disgusted by the whole unmanly excess of the regime he grew up in. It must have hardened his commitment to the self-control and circumspection that Stoicism taught.

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This is the kind of insight one can draw from reading Robertson’s elegant character study. He pulls together Marcus’ own letters and notes with other primary sources to sketch a convincing portrait of the last great Stoic. What’s lovely about this intimate little biography is what’s lovely about the Meditations: it makes Aurelius seem human without making him seem any less impressive. We meet a sensitive young boy, prone to reverie but hardened by circumstance into a steely warrior. Robertson points out that next to the tutors who drilled him in Greek philosophy and rhetoric, his most influential teacher was probably his mother Lucilla, herself an accomplished businesswoman and intellectual. The two of them stuck close together after Marcus’ father died; they had plenty of good friends and loyal patrons, but Lucilla must have known through painful experience that she and her boy had to be ready, at a moment’s notice, to fend for themselves.

Aurelius’ route to the throne was a complicated one, punctuated by a convoluted series of adoptions and deaths. Like Cincinnatus, or George Washington, he wielded power well because he never pursued or even wanted it: he was always longing to get back to his books. “If you had a stepmother and a real mother,” he writes in Meditations, “you would pay your respects to your stepmother, yes…but it’s your real mother you’d go home to. The court…and philosophy: Keep returning to it, to rest in its embrace.” Movingly, Robertson speculates that “mother” came naturally to him as a metaphor for wisdom and learning, since “[t]his must be what Lucilla symbolized for Marcus.” Counseled lovingly by his closest advisors, steadied by his training in philosophy, he matured into a formidable head of state known for serenity under pressure.

His years in command tested that serenity to its limits. Marcus is known as the last of the “five good emperors,” so called less because all of them were sterling characters than because they presided over Rome’s most spectacular boom years. Between Nerva’s accession in A.D. 96 and Marcus’ death from illness in 180, the empire’s territory grew as extensive and well-fortified as it would ever be. From the misty crags of Northern Britain to the sweltering flood plains of Egypt, the realm Aurelius inherited seemed to press hard upon the very margins of the known world. There is even a reference in the Chinese annals of the Han dynasty to envoys from a Roman emperor, probably Aurelius himself. If Julius Caesar had once wept at his inadequacy compared to Alexander the Great, his heirs could now lay claim to a dominion rivaling Alexander’s in size, and surpassing it in staying power.

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Not that Rome was without challengers. During the last ten years of Marcus’ reign, one eastern warlord after another made a bid to yank back territory or independence from Rome. Robertson catalogues the titles Aurelius won for pacifying rebel nations: Armeniacus. Germanicus. Sarmaticus. Lord of the Armenians, the Germans, the Sarmatians. It was not unheard of for an emperor to make a point of refusing honors like these in a grand display of humility, knowing he could expect to have them thrust back at him by a grateful public: as Shakespeare had Mark Antony say of Caesar, “I thrice presented him a kingly crown, / which he did thrice refuse.” Aurelius too demurred to being feted, but private letters from his tutor Marcus Fronto make it clear that in his case, the reluctance was anything but feigned. “The Stoics had taught him to view with indifference the accolades awarded to him,” Robertson writes. In his heart of hearts, he remained a philosopher.

As a ruler, though, he had his detractors. Near the end of his life he faced an insurrection led by Avidius Cassius, a high-born general who despised Marcus for paying no mind to hereditary rank when handing out promotions. Cassius purportedly thought Aurelius was already dead of the plague that was ripping through the empire when he assumed command—but if he believed that story, he would have shed no tears over it. He is represented in a late antique collection of biographies as having been disgusted with what he saw as Marcus’ frivolous obsession over “souls, and virtue, and justice” in the middle of a geopolitical crisis, when “what’s called for is plenty of swords and plenty of practical wisdom.”

Cassius was neither the first nor the last to fault the grateful child of philosophy for musing dreamily over abstractions while his empire descended into anarchy. But it was a charge without merit. Marcus’ devotion to high principle never kept him aloof from the hard realities of politics. Nor did it do too much to tarnish his widespread support, as Cassius learned to his doom when officers from within his own ranks conspired to execute him and put his rebellion down. In Machiavelli’s chapter in The Prince on assassination attempts, Aurelius makes an appearance as the rare emperor who “lived and died honored,” in part because he was “possessed of many virtues which made him respected.” If he was sometimes absorbed in contemplation of those virtues, it was because contemplation kept him steady in the practice of them. Stoicism, to paraphrase Rudyard Kipling, helped Marcus keep his head when all around were losing theirs, and blaming it on him.

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More troubling to posterity is the accusation that Marcus “persecuted Christians,” which has always given pause to readers who would otherwise admire him unreservedly. But his actual record in this regard is tolerably mixed. The most damning reports are also the least credible, having been written long after his reign. Christian fathers who lived under Marcus, like Irenaeus in Lyons and Tertullian in North Africa, give generally favorable assessments of a realm through which Christians were able, by and large, to travel unmolested. Imperial policy was not to go looking for sects to harass, and Marcus was the last person to spearhead a pogrom. He had more important things to worry about.

Still, it was on his watch that Justin Martyr, now a saint, earned his title. Justin was a learned and tenacious apologist. He brought the good news to the city of Rome in the full knowledge that he might be called upon there to honor the cult of the state with a ritual libation, as the law demanded. In what was effectively an act of civil disobedience, he and six of his followers refused to make the offering, stating outright that they would accept the consequences. After trying everything short of repealing the law, the city prefect put them to death.

From a Christian perspective this was a heroic display of conviction on Justin’s part. Evangelists since Saint Paul had maintained that the Gospel must come to Rome, and evangelists since Paul had died bringing it there. To Marcus, who probably rubber-stamped the Justin affair distractedly while attending to more pressing business, it must have seemed like the Christians were asking for pointless trouble. In Meditations he tosses off a disapproving remark about people who go out of their way to die for a cause “through naked obstinacy,” and either he or a later scribe added ruefully: “like the Christians.” With the benefit of hindsight, Marcus was on what you might call the wrong side of history. But his mistake, as Russell Kirk pointed out in his introduction to the collection Gateway to the Stoics (1956), was an honest one, “undertaken out of pure motives, and from a misunderstanding of Christian doctrines.”

Kirk even handed part of the blame for that misunderstanding to “fanatics on the fringe of the then-inchoate Christian church.” Robertson is more measured, but he basically agrees: “Justin had come to the city of his own volition,” he writes, “knowing that the law required him to honor the emperor, whose role included serving as high priest of the state religion.” This was, in other words, the cost of spreading Christianity in Rome; Justin knew that and was willing to pay it. Whether you view this as a glorious deed or a theatrical stunt will depend on how urgently you believe the capital needed Justin’s ministry, and how legitimate his standing was to unseat the city’s gods. It will depend, in other words, on whether you think the spread of Christianity was a net positive for the West.

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And this is the one point on which Robertson seems to me rather less than fair. One almost gets the impression he would have preferred if Marcus’ belief system had won out over Justin’s in the long term, rather than the other way around. He makes a point of comparing Stoicism favorably to Christianity on the subject of slavery: “The New Testament…has little to say against it. The founders of Stoicism, however, considered owning slaves, whether acquired through conquest or purchase, morally wrong.” That’s pretty misleading. The authors of the New Testament were in total agreement with the Stoics that no man was naturally inferior to any other in essence. This was a daring stance to take at the time, but Christians took it just as firmly as Stoics, and for much the same reason—because they believed all humanity descended from one divine father. Paul was so emphatic about this that he quoted the poet Aratus, who had studied under Stoicism’s founding father Zeno, to drive the point home before an audience of captious Greeks: “for ‘we are His offspring,’ as some of your own poets have said” (Acts 17:28).

When it came to slavery as a fixture of the ancient economy, very few Stoics and, until the conversion of Constantine, no Christian had the kind of institutional power to do a thing about it. It would have counted for both groups as one of the many injustices that must be coped with by anyone not in a position to change it. Aurelius, unusually, was in such a position, and to his eternal credit he instituted legal reforms that opened up new routes to manumission for Roman slaves. But abolition was still a distant dream, and it was not the Stoics who would realize it.

When Marcus lay dying, he told his followers to “go to the rising sun: I am already setting.” His Stoic metaphysics would have taught him to view this as one more revolution in the endless turning of the world: “as grain is sown in the earth, and then reaped again,” writes Robertson, “one man is born; another dies.” This cosmic cycle was supposed to roll through eon after eon until the steady-state universe was consumed in fire and itself reborn. But as Marcus’ sun passed over the horizon, a grander revolution was underway: the daylight was fading from the whole pagan culture that Aurelius had lived in and presided over. Not long before, Plutarch had noted the flagging strength of oracles like the one at Delphi, which ran on the fumes of the natural world: “the power they possess is not everlasting and ageless; it is subject to change.” The gods themselves were suffering their own kind of heat death. Meanwhile a new sun could be seen rising in the east over Israel, searing with the messianic fervor of “fanatics” like Justin Martyr. For them life was not a cycle but a blazing arrow, whipping straight toward either heaven or hell. And that meant playing the long game. As the rituals of the old gods drooped into obsolescence, ancient Christians pressed century by century, with otherworldly vigor, toward their wildly implausible goals. These would come in time to include breaking the back of the global slave trade, in the name of a savior who promised “to set the captives free.”

Those words must have sounded like a distant fantasy when they were first cried out in the streets of Jerusalem. But Christian visionaries like the 4th century’s Gregory of Nyssa insisted they were meant in deadly earnest. And so, in the long run, it wasn’t Stoics that morally discredited slavery across the civilized world or put an end to it in the legal codes of modern nations. By the 19th century the religious dream of freedom became an astounding political reality, won at bloody cost by Quaker radicals, Catholic missionaries, and Protestant diplomats. Christians carried forward the best of the Stoics’ legacy in this domain. But they also brought their own thunderous prophecies and far-flung dreams of a divine kingdom to bear on a weary earth.

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If the tables are now turned—if it’s Christianity whose star is on the wane, and pagan philosophies like Stoicism that are getting a reboot—then comparisons between the two are more than merely academic. It’s intriguing, for instance, and a little unnerving to browse the posts on r/Stoicism that deal with thoughts of suicide. No Stoic would have killed himself as an impulsive response to emotional distress. But one of them—Seneca—famously did so when backed into a corner by the raving Emperor Nero. All of them countenanced suicide as an escape route from life when other options seemed exhausted.

Today, in Canada, legalized “Medical Assistance in Dying” (MAiD) has crept insidiously from the hospital ward to the projects, where the socialist magazine Jacobin reported this year that “poverty is driving disabled Canadians to consider MAiD.” The visceral horror we rightly feel at this spectacle suggests that our most deep-set moral instincts remain Christian, not Stoic. One Reddit commenter, weighing the merits of suicide, noted “the current social stigma attached to it.” He spoke more truly than he knew: any aversion we may feel toward abominations like MAiD is a lingering mark of Christianity’s imprint on the Western psyche. The Christian prohibition against self-slaughter is born of the conviction that the human soul’s trajectory points beyond death, so that every action on earth resounds into eternity. The Stoics, who took death as the natural endpoint of their brief arc through the wheeling world, saw no reason not to “make a complete exit from life,” as Marcus put it, once going came to seem better than staying.

This is not to discredit Marcus Aurelius as an exemplar of Roman nobility or to cast aspersions on those who benefit from his wisdom. But it is to say that any return to unadulterated Stoicism as a way of life for the West would represent not progress but regress, of a kind that even now would offend some of our most profound ethical sensibilities. In Marcus Aurelius: The Stoic Emperor we encounter a man of the finest caliber the pagan world had to offer, powerful in his virtues and unfailing in his duty as he saw it. But though we can learn from him, we would not do well to return to his world, even if we could. Our path forward leads elsewhere.