I. He exposes the unscrupulous nature of the proceedings at Ephesus.
From your clemency's letter, which in your love of the Catholic Faith you sent sometime ago to the see of the blessed Apostle Peter, we drew such confidence in your defence of truth and peace that we thought nothing harmful could happen in so plain and well-ordered a matter; especially when those who were sent to the episcopal council, which you ordered to be held at Ephesus, were so fully instructed that, if the bishop of Alexandria had allowed the letters, which they brought either to the holy synod or to Flavian the bishop, to be read in the ears of the bishops, by the declaration of the most pure Faith, which being Divinely inspired we both have received and hold, all noise of disputings would have been so completely hushed that neither ignorance could any longer disport itself, nor jealousy find occasion to do mischief.
But because private interests are consulted under cover of religion, the disloyalty of a few has wrought that which must wound the whole Church. For not from some untrustworthy messenger, but from a most faithful narrator of the things which have been done, Hilary, our deacon, who, lest he should be compelled by force to subscribe to their proceedings, with great difficulty made his escape, we have learned that a great many priests came together at the synod, whose numbers would doubtless have assisted the debate and decision, if he who claimed for himself the chief place had consented to maintain priestly moderation, in order that, according to custom, when all had freely expressed their opinion, after quiet and fair deliberation, that might be ordained which was both agreeable to the Faith and helpful to those in error.
But we have been told that all who had come were not present at the actual decision: for we have learned that some were rejected while others were admitted, who at the aforesaid priest's requisition surrendered themselves to an unrighteous subscription, knowing they would suffer harm unless they obeyed his commands, and that such a resolution was brought forward by him that in attacking one man he might wreak his fury of the whole Church. Which our delegates from the Apostolic See saw to be so blasphemous and opposed to the Catholic Faith that no pressure could force them to assent; for in the same synod they stoutly protested, as they ought, that the Apostolic See would never receive what was being passed: since the whole mystery of the Christian Faith is absolutely destroyed (which Heaven forfend in your Grace's reign), unless this abominable wickedness, which exceeds all former blasphemies, be abolished.
Source: Letters (New Advent)