There was never a document that described or prescribed the current republic: it was all based on agreements (between 'gentlemen') and precedents (the mos maioruum, or 'custom') of our ancestors). Tacitus, in the first words of his Annals, provides us with the main clue: res publica et consulatus (the republic and the consulate). The decline of the Roman Empire With the death of Marcus Aurelius in 180 AD, the government of the empire passed to his twenty-year-old son Lucius Aurelius Commodus. The concept of imperial decline starting with the reign of Commodus is largely adapted from Edward Gibbon's rather arbitrary work, "The Decline and Fall of the Roman Empire" and may have been a bit premature considering that the empire Western civilization lasted for another three centuries. . While the remaining years of the empire, especially the tumultuous third century, were unlikely to feature uninterrupted dynastic rule (largely due to assassinations and civil wars), Commodus' reign marks the end of the adoptive period that provided