Provincia literally means just "sphere of action of a magistrate", and the sense from which our word province is derived is simply the result of the territorial application of the same idea. A "province" is a sphere of action with territorial limits assigned to a magistrate with imperium, and, as such, is outside Italy, for within Italy there were no such geographical limits on the imperium.
It is the unity of command given to the governor within these limits which really constitutes the unity of the province within which may live people actually governed in different ways and standing in varying relationships to Rome. For all of them the governor represents the authority of the Roman state, whether they are Roman citizens resident in the province, members of Roman or Latin colonies or other inhabitants living in their original communities which might or might not have a considerable measure of self-government. It is this fact which explains how the Romans managed to govern their great empire with so few officials. When they acquired territory they did not incorporate it into a coherent administrative system of their own; they left it as a rule in much the same condition as that in which they found it, but subjected great areas of it to the general supervision of a magistrate holding imperium and thus vested with the supreme authority which imperium gave outside the city. The governorship was, in fact, the military command of the Roman general perpetuated as a system of control in times of peace, and the chief limit on the governor's power was not any legal restriction but the physical impossibility of attention to detail with the very small staff which the state put at his disposal.
