As the Republican constitution continued in form unimpaired, so its most essential feature, the magistracy, although subjected to modification, was still an integral element in the administration of Rome and Italy during the Principate. Few radical differences were introduced into the magisterial qualifications or career; the innovations affected only the age for office, the starting point in the _cursus honorum_, and one of the steps in the _certus ordo magistratuum_. The minimum age for the quaestorship was now twenty-five years,[1698] for the praetorship thirty,[1699] and two new qualifications were necessary before the quaestorship could be held. One was membership of the vigintivirate, the aggregate of lower magistracies to which the _sex-et-vigintiviratus_ of the Republic had now shrunk.[1700] The other, perhaps originally a practical rather than a legal qualification, was the tenure of the military tribunate,[1701] the latter being held generally after one of the magistracies in the vigintivirate had been administered. This change, though apparently formal, meant a fundamental alteration in the spirit of the new nobility. The possibilities of culture, to be acquired in the schools of Athens and Rhodes, were now almost extinct. From the age of eighteen the aspirant to the highest honours in the State might be serving with Caesar’s legions on the frontier. It was through the Emperor’s grace that he attained a military position which was at least a practically necessary qualification for the magistracy; at the age of twenty-five the young soldier entered on the race for higher honours; as an ex-praetor, even at times as an ex-quaestor, he might be made the general of a brigade (_legatus legionis_), and from thence proceed to the government of a military, or the administration of a civil, province. Nothing shows more clearly the true military character of the new monarchy than the fact that even its civil and Republican posts were administered by soldiers; nothing explains more adequately the subservience of the Senate than the fact that it was composed mainly of ex-officers, trained in the habits of rigid obedience and in unwavering respect to the _sacramentum_—of men to whom Caesar was not Princeps but Imperator.