33 The same constant union of St. Cyril with the Apostolic See is clearly apparent in all that he did to effect and consolidate reunion with the Bishops of the Province of Antioch. Although Our Predecessor St. Celestine approved and ratified all that the Patriarch of Alexandria had done at the Council of Ephesus, he made an exception for the sentence of excommunication which the President of the Council, together with the other Fathers, had passed upon the Antiochenes. The Sovereign Pontiff wrote: With regard to those who appear to have been of one mind and one impiety with Nestorius, . . . We have read the sentence you have passed upon them. Nevertheless, We also decree what seems to Us opportune. In these cases many circumstances have to be considered which the Apostolic See has always borne in mind . . . Should the Bishop of Antioch offer hope of being corrected, We would have Your Fraternity come to some Agreement with him by letter. . . . We must trust that by the divine mercy all may return to the way of truth. And it was in obedience to this instruction of the Roman See that St. Cyril began to take measures for bringing about reunion with the Bishops of the Province of Antioch.
Source: Orientalis Ecclesiae (Vatican.va)