St. Leo the Great deserves his title; he has a claim to be the greatest Pope since St. Peter. There is an argument to be made for his being the Pope who definitively established the Petrine claims. In his Essay on the Development of  Christian Doctrine, Newman deals with the part he played at the Council of Chalcedon in AD 451. Here I offer some updates from recent scholarship to what was known when Newman wrote.

The Council was called by the Emperor Marcian to sort out the mess left by the second Council of Ephesus, held in 449 which had ended in chaos. The successor of St. Cyril of Alexandria, Patriarch Dioscorus, had there secured the declaration that the monk Eutyches, who had been condemned for Christological heresy, was in fact orthodox. The decision was over-turned at Chalcedon, something the Alexandrian and other Eastern Churches have never accepted. It was the first great schism. Central to it was the definition of the two natures of Christ offered by Pope Leo.

When the Fathers at Chalcedon declared ‘Peter has spoken through Leo’ what did this mean? Since 1054 Orthodox Christians from Greece and Russia have contested the plain meaning of the words; since they also contest the plain meaning of Matthew 16:18; this occasions no surprise.

At the heart of much of the dispute is the question of the jurisdiction held by the early Popes. Canon 3 of the Council of Sardica (343)  allowed appeals to Rome from the decision of a local bishop (See H. Hess, The early development of Canon law and the Council of Sardica (2002), esp. pp. 212-214.) This was a codification of Rome’s response to the case presented by St. Athanasius in 341. In his Apologia ad Constantium Athanasius tells us that after he was expelled from Alexandria by the Arian-inclined authorities he went to Rome to appeal against the judgement of the Eusebian bishops at Tyre who had deposed him and other orthodox bishops, including Paul of Constantinople. Pope Julius (337-352) presided over a council of 50 bishops in 341 and overturned the Tyrian verdict; Athanasius, Paul and their fellows returned to their Sees and were reinstated.

It might be noted here that his opponents were just as interested in being in Rome’s favour as two of them, Ursacius of Singiduum and Valens of Muras wrote to beg forgiveness. (See Athanasius, Apologia contra Arianos 58 for the texts).

That such a view, that is that Rome had appellate jurisdiction from other bishoprices, was not confined to the West is shown not only by the appeal to it from Athanasius and Paul of Constantinople, it is present in St. Jerome’s writings. Its most recent manifestation was one with which the young Leo was personally familiar as he had been involved with it. After the Council of Ephesus (the ‘robber council’) Flavian, Theodoret and Eusebius had written to Pope Celestine to protest against their deposition and to seek his approval to their restoration. They did so in view of the fact that before that Council the Pope’s legates had declared that: ‘Peter, the prince and leader of the apostles [who] was given the power of loosing and binding sins’ continued to live and judge in his successors. This was read into the record at Chalcedon.

So what did Leo understand by the words that ‘Peter’ spoke through him? To this we shall turn next.