I. There is no need to open the question of doctrine again now.
Your clemency's letter, which was full of vigorous faith and of the light of truth, I have respectfully received, which I wish I could obey, even in the matter of my personal attendance, which your Majesty thinks necessary; for then I should gain the greater advantage from the sight of your splendour. But I believe you will approve of my view when reason has shown it preferable. For since with holy and spiritual zeal you consistently maintain the Church's peace, and nothing is more conducive to the defence of the Faith than to adhere to those things which have been incontrovertibly defined under the unceasing guidance of the Holy Spirit, we shall seem to be doing our best to upset the decrees, and at the bidding of a heretic's petition to overthrow the authorities which the universal Church has adopted, and thus to remove all limits from the conflicts of Churches, and giving full rein to rebellion, to extend rather than appease contentions.
And hence because after the disgraceful scenes at the synod of Ephesus, whereat through the wickedness of Dioscorus the Catholic Faith was rejected, and Eutyches' heresy accepted, nothing more useful could be devised for the preservation of the Christian Faith than that the holy Synod of Chalcedon should rescind his wicked acts, and that such care should be bestowed thereat on heavenly doctrine, that nothing should linger in any one's mind in disagreement with the utterances of either the Prophets or the Apostles, such moderation of course being observed that only the persistent rebels should be cast off from the unity of the Church, and no one who was penitent should be denied pardon, what more in accordance with men's expectations or with religion will your Majesty be able to decree, than that no one henceforth be permitted to attack what has been determined by decrees which are Divine rather than human, lest they be truly worthy but to lose God's gift, who have dared to doubt concerning His Truth?
Source: Letters (New Advent)