A long tradition of studies has represented the third century as a watershed, or at least as a moment of intersection separating two radically different, even opposed, worlds. More specifically with regard to the imperial authority, it has identified two different ways of governing the empire, of legitimating the exercise of imperial power and even of providing a selfrepresentation. According to this view, the clean break took the form of a ‘crisis’, which to a certain extent already revealed some of the weaknesses that eventually brought about the dissolution of a unified imperial organism in the west during the fifth century. It has also been held that such contrasting methods of exercising power corresponded to equally radical differences in how the administration was organized, at both central and peripheral levels. Indeed, it has even been claimed in a general way that it was during the fourth century, with the increasingly autocratic developments in imperial power, that we begin to detect a sharper distinction between government and administration, between political directive and administrative implementation – a distinction so characteristic of modern states with their division of powers.

According to this traditional view, therefore, the difference between the administrative organization of the principate and that of the late antique empire was both qualitative and quantitative. The second-century empire was run by provincial governors of senatorial rank, equestrian procurators and an extensive familia Caesaris. That of the third century, on the other hand, saw not only the increasing importance of staff from the army ranks, such as the beneficiarii operating in the legates' officia, but also the exclusion of senators from military command, a process that eventually – during the subsequent tetrarchic period – led to a clear separation of duties between the civil and military staff involved in provincial government.