Ammianus Marcellinus, by common consent the last great historian of Rome, rounds off his obituary notice of the emperor Constantius II (d. 361) with the following observation:The plain simplicity of Christianity he obscured by an old woman's superstition; by intricate investigation instead of seriously trying to reconcile, he stirred up very many disputes, and as these spread widely he nourished them with arguments about words; with the result that crowds of bishops rushed hither and thither by means of public mounts on their way to synods (as they call them), and while he tried to make all their worship conform to his own will, he cut the sinews of the public transport service.This is a perceptive judgement of the ecclesiastical politics of the reign of Constantius, remarkable in a pagan writer, and of exceptional significance in that it lies outside those very ‘arguments about words’ which contaminate all the Christian assessments of this emperor. Although Ammianus is unsympathetic to Constantius, he manages succinctly to grasp the basic drift of imperial policy, inherited from Constantine himself, of trying to enforce the emperor's view of doctrinal and ecclesiastical unity by the summoning of repeated episcopal councils and browbeating the bishops into agreement — thus paying lip-service to the independence of the church's judgements. To the observant outsider, this process was notable above all for the burden it placed on thecursus publicus, as the bishops went about their business around the empire now provided with officialevectiones; and Ammianus' comment finds confirmation in the letter issued by eastern bishops attending one of the many councils of Constantius' reign, that at Sardica in 343, who complained of the ‘attrition’ of the transport service caused by the imperial summons.