XVII. (16) About the writings of Dictinius.
Under the last head a just complaint was made that the treatises of Dictinius which he wrote in agreement with Priscillian's tenets were read by many with veneration: for if they think any respect is due to Dictinius' memory, they ought to admire his restoration rather than his fall. Accordingly it is not Dictinius but Priscillian that they read: and they approve of what he wrote in error, not what he preferred after recantation. But let no one venture to do this with impunity, nor let any one be reckoned among Catholics who makes use of writings that have been condemned not by the Catholic Church alone but by the author himself as well. Let not those who have gone astray be allowed to make a fictitious show, and under the veil of the Christian name shirk the provisions of the imperial decrees. For they attach themselves to the Catholic Church with all this difference of opinion in their heart, with the object of both making such converts as they can, and escaping the rigour of the law by passing themselves off as ours. This is done by Priscillianists and Manichæans alike; for there is such a close bond of union between the two that they are distinct only in name, but in their blasphemies are found at one: because although the Manichæans reject the Old Testament which the others pretend to accept, yet the purpose of both tends to the same end, seeing that the one side corrupts while receiving what the other assails and rejects.
But in their abominable mysteries, which the more unclean they are, are so much the more carefully concealed, their crime is but one, their filthy-mindedness one, and their foul conduct similar. And although we blush to speak so plainly, yet we have tracked it out with the most painful searches, and exposed it by the confession of Manichæans who have been arrested, and thus brought it to the public knowledge: lest by any means it might seem matter of doubt, although it has been disclosed by the mouth of the men themselves, who had performed the crime, in our court, which was attended not only by a large gathering of priests, but also by men of repute and dignity, and a certain number of the senate and the people, even as the missive which we have addressed to you, beloved, shows to have been done. And there has been found out and widely published about the immoral practices of the Priscillianists just what was also found out about the foul wickedness of the Manichæans. For they who are throughout on a level of depravity in their ideas, cannot be unlike in their religious matters.
So having run through all that the detailed refutation contains, with which the contents of the memorial of their views does not disagree, we have, I think, satisfactorily shown what our opinion on the matters which you, brother, have referred to us, and how unbearable it is if such blasphemous errors find acceptance in the hearts even of some priests, or to put it more mildly, are not actively opposed by them. With what conscience can they maintain the honourable position which has been given them, who do not labour for the souls entrusted to them? Beasts rush in, and they do not close the fold. Robbers lay wait, and they set no watch. Diseases multiply, and they seek out no remedies. But when in addition they refuse assent to those who act more warily, and shrink from anathematizing by their written confession blasphemies which the whole world has already condemned, what do they wish men to understand except that they are not of the number of the brethren, but on the enemy's side?
Source: Letters (New Advent)