The Roman state was still a limited sovereignty of the people; so limited, indeed, that the people, i.e. the patricio-plebeian _populus Romanus_, was dependent, not merely for the expression of its will, but even for its _existence_, on the life of its supreme magistrates. In the practice of the Republic down to its closing days, the cessation of the consulate, by the non-election or the death of its occupants, caused the suspension of the life of the state. The people could not meet except under the shadow of the higher _imperium_ or _auspicia_—those of lesser patrician magistrates were of no avail; for the praetor, though technically a colleague of the consuls,[596] could not hold the consular elections[597]—and the city was in a state of suspended animation until the _auspicia_ in all their purity should be restored, were it but to a single man. The auspices, meanwhile, have returned to the “fathers,”[598] and it is they only who can restore them. The first fundamental element, therefore, in the theory of the Roman constitution, however absurd it may seem, is that ultimate sovereignty rests with the patrician members of the Senate.[599] How this theory was put into practice, and what modifications the practice had undergone since the time of the monarchy, may be seen by examining the procedure consequent on a Republican _interregnum_. The conditions requisite for an _interregnum_ were the non-existence of consuls, or magistrates with consular power, or a dictator. The retirement of all the other so-called patrician magistrates, i.e. _magistratus populi_, was another necessary preliminary, for the auspices could not return to the _patres_ so long as they were held, whether as _majora_ or _minora auspicia_,[600] by a patrician magistrate.[601] Hence, when a sudden occasion arose for the appointment of an interrex, it was the duty of the Senate to give notice to the patrician magistrates and to request them to retire from office.[602] The plebeian magistrates still remained in the exercise of their functions. It was, in the later Republic, the Senate which took all further necessary action. In the early Republic there was no possibility of its being summoned, and the patrician senators met at their own discretion to appoint the interrex. But after the tribune, who was still in office, had gained the right of transacting business with the Senate, it was he who put the question, and the Senate who suggested that the _patricii_ should meet for the purpose. From this time onwards the electors felt no obligation to meet except on the suggestion of the Senate.[603]