As the Roman Empire waned the Church waxed. Inevitably it was a Church deeply affected by Romanitas. When the Empire became Christian, if that is the right way of putting it, under Constantine the political centre moved east to the new capital of the Bosphorous, the Washington or Brasilia of the new era. Byzantium became the royal city, Rome the urbs ecclesiae, the city of the Church. Inevitably the head of the city of the Church, in view of the hierarchical ideology coming into increasing favour, was taken more and more seriously as successor of Peter. The climax of this early papalism is the pontificate of Leo the Great and the reception accorded to his letter or tome at the council of Chalcedon: the tome and the council set the seal on orthodox Christology. However this undoubted display of successful authority must be seen in its context. Behind the council’s Christologi-cal decrees lay more than a century of conciliar activity and the production of what are still the orthodox credal formularies: to all this Rome contributed veiy little. The canon of Scripture had been debated and disputed: the authoritative work of deciding what was to be included and what was to be excluded was done without reference to Rome. It is Leo’s intervention which is unusual. His predecessors had not made much effort to settle doctrinal disputes: one feels by this time Christians felt this sort of thing was the job of gatherings of bishops. Leo is unlikely to have felt very differently but as the events of the last generation had shown, the problems of theology had become vital political issues and if Rome had not intervened it seems unlikely agreement of any kind would have been reached.