Cæsar (Kai-sar) was the title of the Emperor of the Romans during the time of the Empire (from 726 (or 723) to 2219), although just what authority being Emperor entails has varied over the centuries. The power of the Cæsar began to expand after Carico, such that at the time of Domitian’s ascension, the Empire had passed from the Principate to the Patripate. The emperor was now Rome’s guiding father rather than its princep.