Roman Emperor and philosopher Marcus Aurelius (/ɑːˈriːliəs/ or /ɑːˈriːljəs/; Latin: Marcus Aurelius Antoninus Augustus; 26 April 121 – 17 March 180) was a 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. After his father, the praetor Marcus Annius Verus (III) (the nephew of the reigning Emperor Hadrian), died, Marcus was raised by his mother Domitia Lucilla and grandfather Marcus Annius Verus (II). Following the death of Hadrian's adoptive heir apparent Aelius Caesar in 138, the emperor adopted Marcus' uncle Antoninus Pius as his new heir. In turn, Antoninus adopted Marcus and the son of Aelius, Lucius (later to rule as Emperor Lucius Verus alongside Marcus). Hadrian died that year and Antoninus became emperor. 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. Lucius Verus may have died from the plague in 169. Unlike some of his predecessors, Marcus chose not to adopt an heir. His children included Lucilla, who married Lucius, 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.