II. In the settlement of this matter that moderation must be observed which was entirely absent at Ephesus.
For, as I have very often stated in letters from the beginning of this matter, I have desired that such moderation should be observed in the midst of discordant views and carnal jealousies that, while nothing should be allowed to be wrested from or added to the purity of the Faith, yet the remedy of pardon should be granted to those who return to unity and peace. Because the works of the devil are then more effectually destroyed when men's hearts are recalled to the love of God and their neighbours.
But how contrary to my warnings and entreaties were their actions then, it is a long story to explain, nor is the need to put down in the pages of a letter all that was allowed to be perpetrated in that meeting, not of judges but of robbers, at Ephesus; where the chief men of the synod spared neither those brethren who opposed them nor those who assented to them, seeing that for the breaking down of the Catholic Faith and the strengthening of execrable heresy, they stripped some of their rightful rank and tainted others with complicity in guilt; and surely their cruelty was worse to those whom by persuasion they divorced from innocence, than to those whom by persecution they made blessed confessors.
Source: Letters (New Advent)