"If," writes Roman historian Edward Gibbon in his A History of the Decline and Fall of the Roman Empire," a man were called upon to fix the period in the history of the world when the condition of the human race was most happy and prosperous, he would, without hesitation, name that which elapsed from the death of Domitian to the accession of Commodus;" the period from 98 to 180 A.D. Yet in the next century the Roman empire crumbled. There were civil wars between 180 and 285 A.D. Of twenty-seven emperors or would-be emperors all but two met vi ....