agentes in rebus
The detested frumentarii (see postal service) were abolished by Diocletian, but were soon replaced by ‘agents’ perhaps purposely ill-defined, who likewise served as couriers between the court (comitatus) and the provinces. They were civilians, but they enrolled as troopers and rose by seniority through the same grades as non-commissioned soldiers. As they became more senior, they served as curiosi supervising the public post, and finally as chiefs of staff (principes) to the praetorian prefects, urban perfects (see praefectus praetorio; praefectus urbi), proconsuls, vicarii, and eastern duces (see dux). Their duties included making reports on the provinces, and they gained a reputation as secret police (Aur. Vict. Caes. 39. 44) and for extorting illicit tips (Lib., Or. 14. 14), but their real role was to be the trusted emissaries of the central government. Ponticianus, a pious Christian instrumental in the conversion of St Augustine, was an agens in rebus; Augustine's friend and fellow-townsman Evodius was another. By the mid-4th cent. ce they formed a college (schola) under the magister officiorum, hence their name (in Greek) as ‘the master's men’. They were practically abolished by Julian, but under his successors they reached an establishment of more than a thousand. There were many applicants for the career, and they were carefully selected. By the time of the Theodosian Code (and probably earlier), freedmen, Jews, and heretics were excluded; relatives of agentes had preference for entry, and various dignitaries had limited rights of nomination.