The rank and station of Agrippina in Roman society was even higher than that of her husband. She was the sister of the emperor. The name of the emperor, her brother, was Caligula. He was the third in the series of Roman emperors, Augustus Cæsar, the successor of Julius Cæsar, having been the first. The term emperor, however, had a very different meaning in those days, from its present import. It seems to denote now a sovereign ruler, who exercises officially a general jurisdiction which extends over the whole government of the state. In the days of the Romans it included, in theory at least, only _military_ command. The word was _imperator_, which meant _commander_; and the station which it denoted was simply that of general-in-chief over the military forces of the republic. In the early periods of the Roman history, every possible precaution was taken to keep the military power in a condition of very strict subordination to the authority of the civil magistrate and of law. Very stringent regulations were adopted to secure this end. No portion of the army, except such small detachments as were required for preserving order within the walls, was allowed to approach the city. Great commanders, in returning from their victorious campaigns, were obliged to halt and encamp at some distance from the gates, and there await the orders of the Roman Senate. The _Senate_ was, in theory, the great repository of political power. This Senate was not, however, as the word might seem in modern times to denote, a well-defined and compact body of legislators, designated individually to the office, but rather a class of hereditary nobles, very numerous, and deriving their power from immemorial usage, and from that strange and unaccountable feeling of deference and awe with which the mass of mankind always look up to an established, and especially an ancient, aristocracy. The Senate were accustomed to convene at stated times, in assemblages which were, sometimes, conducted with a proper degree of formality and order, and sometimes on the other hand, exhibited scenes of great tumult and confusion. Their power, however, whether regularly or irregularly exercised, was supreme. They issued edicts, they enacted laws, they allotted provinces, they made peace, and they declared war. The armies, and the generals who commanded them, were the _agents_ employed to do their bidding.