III. The Synod of Chalcedon, which met for one purpose, ought never to have been used for another.
Accordingly these things which are found to be contrary to those most holy canons are exceedingly unprincipled and misguided. This haughty arrogance tends to the disturbance of the whole Church, which has purposed so to misuse a synodal council, as by wicked arguments to over-persuade, or by intimidation to compel, the brethren to agree with it, when they had been summoned simply on a matter of Faith, and had come to a decision on the subject which was to engage their care. For it was on this ground that our brothers sent by the Apostolic see, who presided in our stead at the synod with commendable firmness, withstood their illegal attempts, openly protesting against the introduction of any reprehensible innovation contrary to the enactments of the Council of Nicæa.
And there can be no doubt about their opposition, seeing that you yourself in your epistle complain of their wish to contravene your attempts. And therein indeed you greatly commend them to me by thus writing, whereas you accuse yourself in refusing to obey them concerning your unlawful designs, vainly seeking what cannot be granted, and craving what is bad for your soul's health, and can never win our consent. For may I never be guilty of assisting so wrong a desire, which ought rather to be subverted by my aid, and that of all who think not high things, but agree with the lowly.
Source: Letters (New Advent)