Marcus Aurelius (121 - 180). Marcus Aurelius was Roman emperor from 161 to 180 and a Stoic philosopher. He was the last of the rulers known as the Five Good Emperors, and the last emperor of the Pax Romana, an age of relative peace and stability for the Roman Empire. He served as Roman consul in 140, 145, and 161. The son of the praetor Marcus Annius Verus and the wealthy heiress Domitia Lucilla, Marcus was raised by his grandfather, Marcus Annius Verus, after his father died. His uncle, Antoninus Pius, adopted him shortly before becoming emperor in 138. Now heir to the throne, Marcus studied Greek and Latin under tutors such as Herodes Atticus and Marcus Cornelius Fronto. He kept in close correspondence with Fronto for many years afterwards. Marcus married Antoninus' daughter Faustina in 145. Antoninus died following an illness in 161. The reign of Marcus Aurelius was marked by military conflict. In the East, the Roman Empire fought successfully with a revitalized Parthian Empire and the rebel Kingdom of Armenia. Marcus defeated the Marcomanni, Quadi, and Sarmatian Iazyges in the Marcomannic Wars; however, these and other Germanic peoples began to represent a troubling reality for the Empire. He modified the silver purity of the Roman currency, the denarius. The persecution of Christians in the Roman Empire is believed to have increased during his reign. The Antonine Plague broke out in 165 or 166 and devastated the population of the Roman Empire, causing the deaths of five million people. Unlike some of his predecessors, Marcus chose not to adopt an heir. His children included Lucilla and Commodus, whose succession after Marcus has become a subject of debate among both contemporary and modern historians. The Column and Equestrian Statue of Marcus Aurelius still stand in Rome, where they were erected in celebration of his military victories. Meditations, the writings of the philosopher-as contemporary biographers called Marcus-are a significant source of the modern understanding of ancient Stoic philosophy. They have been praised by fellow writers, philosophers, monarchs, and politicians centuries after his death. The major sources depicting the life and rule of Marcus are patchy and frequently unreliable. The most important group of sources, the biographies contained in the Historia Augusta, claim to be written by a group of authors at the turn of the 4th century AD, but were in fact written by a single author from about 395 AD. The later biographies and the biographies of subordinate emperors and usurpers are unreliable, but the earlier biographies, derived primarily from now-lost earlier sources, are much more accurate. For Marcus' life and rule, the biographies of Hadrian, Antoninus, Marcus, and Lucius are largely reliable, but those of Aelius Verus and Avidius Cassius are not. A body of correspondence between Marcus' tutor Fronto and various Antonine officials survives in a series of patchy manuscripts, covering the period from c. 138 to 166. Marcus' own Meditations offer a window on his inner life, but are largely undateable and make few specific references to worldly affairs. The main narrative source for the period is Cassius Dio, a Greek senator from Bithynian Nicaea who wrote a history of Rome from its founding to 229 in eighty books. Dio is vital for the military history of the period, but his senatorial prejudices and strong opposition to imperial expansion obscure his perspective. Some other literary sources provide specific details: the writings of the physician Galen on the habits of the Antonine elite, the orations of Aelius Aristides on the temper of the times, and the constitutions preserved in the Digest and Codex Justinianeus on Marcus' legal work. Inscriptions and coin finds supplement the literary sources. Main article: Early life of Marcus Aurelius Marcus was born in Rome on 26 April 121. His name at birth was supposedly Marcus Annius Verus, but some sources assign this name to him upon his father's death and unofficial adoption by his grandfather, upon his coming of age, or at the time of his marriage. He may have been known as Marcus Annius Catilius Severus, at birth or at some point in his youth, or Marcus Catilius Severus Annius Verus.