History of the Roman Empire founder of the brief Flavian dynasty, to be followed by the Nerva–Antonine dynasty which produced the "Five Good Emperors": Nerva, Trajan, Hadrian, Antoninus Pius and the philosophically inclined Marcus Aurelius. In the view of the Greek historian Dio Cassius, a contemporary observer, the accession of the emperor Commodus in 180 AD marked the descent "from a kingdom of gold to one of rust and iron"—a famous comment which has led some historians, notably Edward Gibbon, to take Commodus' reign as the beginning of the decline of the Roman Empire. In 212, during the reign of Caracalla, Roman citizenship was granted
Historiography of the fall of the Western Roman Empire on them. Gibbon held that Christianity contributed to this shift by making the populace less interested in the worldly "here-and-now" because it was willing to wait for the rewards of heaven. Writing in the 5th century, the Roman historian Vegetius pleaded for reform of what must have been a greatly weakened army. The historian Arther Ferrill has suggested that the Roman Empire – particularly the military – declined largely as a result of an influx of Germanic mercenaries into the ranks of the legions. This "Germanization" and the resultant cultural dilution or "barbarization" led not only to a decline in