When we first begin to see clearly into the working of the Roman State, what chiefly strikes us is the unlimited power of the magistrate in all the departments of government. Just as the head of the family had an absolute power over its members, so had the king (_rex_) an unlimited power over the citizens. In the family the word for this power was _potestas_, but in the State it was called _imperium_—one of the greatest words ever coined, surviving to the present day in many familiar forms. For the Roman it expressed more strikingly than any other the idea of discipline in the State: it stamped on his mind the inherited conviction that lawful authority must be implicitly obeyed. Not unlawful authority, ill gotten by fraud or violence; for such power the word _imperium_ could never be used: but authority entrusted to an individual by the human members of the State, and sanctioned by the consent of its divine members. For the _imperium_ must be conferred upon its holder by an act of the people, and the gods must give their consent by favourable omens; both processes, the passing of the law, and the obtaining of the _auspicia_, must be gone through according to certain traditional methods, and the slightest flaw in these would make the choice of the magistrate invalid. But once legally in his hands, the _imperium_ was irresistible; its outward symbols, the rods and axes of the lictors, accompanied its holder wherever he went, to remind the Roman that the first duty of a citizen was obedience to constituted authority. This word _imperium_ stood for three different kinds of power. First, the king was supreme in matters of religion, for he was responsible for the good relations between the human and divine inhabitants of the city, for “the peace of the gods” as it was called. If this peace, or covenant, were not kept up, it was believed that the State could not prosper—the very life of the State depended on it. But now let us note a point of the utmost importance in the development of Roman public life. The king could not perform this duty entirely by himself; no single man could have the necessary knowledge of all the details of ancient religious custom. So he was assisted by a small board of skilled experts called _pontifices_, perhaps also by another board of _augurs_, skilled in the methods of discovering the divine will by omens. Thus the _imperium_ in religious matters, though still legally unlimited, was saved from becoming arbitrary and violating ancestral custom: the king is entrusted with power which he uses in accordance with the advice of sages.