But a final observation occurs to us at this point, again showing the very uncertain and changeable nature of this consular government. In mentioning the chief authorities of the Commune, almost all documents refer to them as "_Consules seu rectores vel rector_," with the addition, at a later date, of "_Potestas sive dominator_."[138] All these terms had a very general meaning at the period. Nevertheless, there must have been some reason for employing the formula--Consuls or Rectors or _Potestà_--in treaties of peace, or alliance, or state documents of high importance; and probably a special reason, seeing that we often find the formula ending as follows: "_Consules qui pro tempore erint, et si non erint_," the Rectors or the _Potestà_ or the Consuls of the guilds were to act in their stead. Why so much vagueness in indicating the chief magistrate of the Republic? Only one explanation is possible. The real practical government of the city was carried on by the various associations; the office of Consul had few attributes and never attained the power and importance due to a central government, as conceived in the modern sense. The same remark may be also applied to the Priors, the Ancients, and other officers of later date; but it is specially true as applied to the consuls, under whom the various civic societies were first united in a single government. Therefore, to meet the eventuality of no Consuls being in office at the moment, it was provided that the Rectors of the Towers or of the guilds should naturally assume the power directly emanating from them. But as no public acts performed in the name of the Rectors are extant, we may conclude that the contingency arranged for seldom arose.