MARCVS
AVRELIVS

Marcus Aurelius came to the throne through a chain of adoptions engineered fifty years before he was old enough to understand it.

In 138 AD, Hadrian, nearing death and without a biological heir, adopted Antoninus Pius on the condition that Antoninus in turn adopt two boys: the seventeen-year-old Marcus and the seven-year-old Lucius Verus. The mechanism was characteristically Hadrianic, deliberate, long-sighted, and cold. It produced the longest continuous succession of peaceful imperial transitions in Roman history.

Antoninus reigned twenty-three years, the most placid reign of the imperial era. When he died in March 161 AD, Marcus acceded. His first act was to insist that Lucius Verus, his adoptive brother, share the throne with him as co-emperor. It was the first formal joint emperorship in Roman history. Verus died of plague in 169 AD. Marcus reigned alone thereafter.

He was forty years old when he came to power. He had trained for it since the age of seventeen. And within months of his accession, the Parthians invaded Armenia, the Tiber flooded Rome, and the plague began.

Marcus inherited the empire at its greatest territorial extent and reigned through its first serious challenge. The Parthian War of 161 to 166 AD was won, under the command of Verus's general Gaius Avidius Cassius, but the returning legions brought back the Antonine Plague, probably smallpox, which killed between five and ten million people across the empire over the next fifteen years. It was the worst demographic catastrophe in Roman imperial history.

In 166 AD, while the plague still raged, the Germanic tribes of the Danube frontier, the Marcomanni, the Quadi, and the Iazyges, crossed into Roman territory in force for the first time in generations. Marcus spent most of the remaining fourteen years of his life on the northern frontier, commanding legions in the field in the Marcomannic Wars. He was not a natural soldier. He was a bookish Stoic in middle age, asthmatic, in pain much of the time. He commanded anyway.

It was during these campaigns, in a tent on the banks of the Gran in what is now Hungary, that he composed the private notebook that has come down to us as the Meditations, Τὰ εἰς ἑαυτόν, "things addressed to himself." He wrote in Greek, the language of philosophy. He was not writing for publication. He was writing to keep himself sane.

His army followed him. His empire held. The plague eventually receded. The Danube was stabilized. By the time of his death, the frontier was quiet and Rome had survived its first great shock as an imperial system.

Marcus's administrative record was solid rather than spectacular. He continued the legal reforms of Hadrian and Antoninus, extending protections for slaves and minors, requiring judicial review in capital cases, limiting abuses of imperial prosecution. He was scrupulous about consulting the Senate, which had by his time become largely ceremonial but which he treated as if it were not. He sold imperial treasures, including his wife Faustina's jewelry, rather than raise extraordinary taxes to finance the German wars.

He also, without apparent compunction, authorized the persecution of Christians. His own letters and the acts of his governors record martyrdoms at Lyon in 177 AD that were among the worst of the second century. Marcus seems to have regarded Christianity as a form of stubborn irrationality that threatened civic religion and therefore civic order. The Stoic emperor who wrote that all humans are brothers was also, in this matter, a conventional Roman of his class.

His great personal failure was his son. Commodus, born in 161 AD on the day of his father's accession, was a disappointment from adolescence onward. Cruel, vain, athletic rather than intellectual, he was everything Marcus was not. Marcus knew. He chose Commodus as successor anyway, breaking the century-old Nerva-Antonine practice of adoptive succession from outside the imperial family. The reasons remain debated. Dynastic affection. Political calculation. Fear of civil war if he passed Commodus over. All three, probably.

The decision cost Rome the system Hadrian had engineered. Commodus would reign for twelve years, badly, and his assassination would open the door to the Severan dynasty, the Crisis of the Third Century, and everything that followed.

Marcus died on campaign on 17 March 180 AD, at the military base of Vindobona on the Danube, probably of the plague that had haunted his reign from its first year. He was fifty-eight years old. His last recorded words, to a tribune asking for the day's password, were vade ad orientem, sol enim mihi iam occidit. "Go to the rising sun. Mine has already set."

The Senate deified him immediately. His equestrian statue, cast in gilded bronze, survived the collapse of the Western Empire and the Middle Ages because Christian Rome mistook him for Constantine. It now stands in the Capitoline Museum, the only large-scale Roman bronze equestrian statue to come down to us intact.

The Meditations circulated for more than a millennium as a minor philosophical curiosity before their modern rediscovery. The first printed edition appeared in Zurich in 1559. Since the eighteenth century, they have been continuously in print in every major language. No other Roman emperor has a private notebook like this. No other emperor, in fact, left anything comparable. The book Marcus wrote to keep himself sane on the Danube frontier has become one of the most-read works of ancient literature and a foundational text of modern Stoicism's revival.

Gibbon began his Decline and Fall with Marcus's reign because, in his famous judgment, "the period in the history of the world during which the condition of the human race was most happy and prosperous" extended from the accession of Nerva to the death of Marcus Aurelius. Everything afterward, in Gibbon's telling, was descent. The judgment is too neat. But it places Marcus correctly. He is the last emperor of the old Rome, the one in which the succession worked and the philosophy matched the practice and the frontier held.

He is the philosopher-king of Plato's Republic, the only one who ever existed. He did not enjoy the role. He did it anyway.