In 139 AD, Marcus was given the rank of Caesar and later married Faustina Junior, the daughter of Antoninus Pius, in 146 AD. The following year, Marcus received the tribunician power.

With the death of Antoninus Pius, Marcus Aurelius succeeded to the throne without incident on March 7th, 161 AD. He immediately extended the rank of co-emperor (Augustus) to Lucius Verus who had also been adopted by Antoninus Pius at the same time as Marcus Aurelius. With Lucius as his joint partner, a political marraige was arranged and Lucius was thus betrothed to his daughter Lucilla.

The Roman emperor Marcus Aurelius was perhaps the only true philosopher- king in the history of the world. He was not an original nor a systematic philosopher, but in his meditations, a series of notes to himself, he formulated his pantheist Stoic beliefs with a passionate religious conviction.

He shared the basic Stoic belief in the divinity of the cosmos as an intelligent being with a soul, and stressed (perhaps too fatalistically) the harmony of all things and the importance of resigning oneself to whatever happened.

Marcus Aurelius reigned from 161 AD to 180 AD. He seems to have been a good and conscientious ruler who was magnanimous towards his enemies. He banned informers, stamped down hard on corruption, and freed slaves at every opportunity. Although he tolerated the circus, he ordered gladiators to fight with blunted points. Needing extra funds for his wars in Eastern Europe, he refused to raise taxes but instead held a public auction of his own golden tableware and of his wife's silk and gold embroidered dresses.

The Meditations were written day by day, in every situation including war. They often appear to be responses to the stress of supreme power, from the imminent fear of death in battle, to the trials of everyday life.

With hindsight Marcus' greatest omission was that he did not impose Stoicism as the imperial religion, with as much rigour as Theodosius later imposed Christianity. Had he done so, the history of the world might have turned out very differently. But the fact that he was more tolerant might be regarded as another of his virtues.

Marcus' greatest trial was his son Commodus, who succeeded him in a disastrous reign that rivalled Nero's for corruption and cruelty. One report of Marcus' death suggests he was poisoned by doctors acting on Commodus' behalf.

Marcus Aurelius died in 180 AD, at the age of 59