Rufinus's Epilogue to Pamphilus the Martyr's Apology for Origen
Such are the complaints which he made while still living, and while he was still able to detect the corruptions and falsifications which had been made in his books. There is another letter of his, in which I remember to have read a complaint of the falsifying of his writings; but I have not a copy of it at hand, otherwise I could add to those which I have quoted a second testimony in favour of his good faith and veracity direct from himself. But I think that I have said enough to satisfy those who listen to what is said, not in the interest of strife and detraction, but in that of a love of truth. I have shown and proved in the case of the saintly men of whom I have made mention, and of whose orthodoxy is no question, that, where the tenor of a book is presumably right, anything which is found in it contrary to the faith of the church is more properly believed to have been inserted by heretics than to have been written by the author: and I cannot think it an absurd demand that the same thing should be believed in the case of Origen, not only because the argument is similar but because of the witness given by himself in the complaints which I have brought out from his writings: otherwise we must believe that, like a silly or insane person, he has written in contradiction to himself.
As to the possibility that the heretics may have acted in the violent manner supposed, such wickedness may easily be believed of them. They have given a specimen of it, which makes it credible in the present case, in the fact that they have been unable to keep off their impious hands even from the sacred words of the Gospel. Any one who has a mind to see how they have acted in the case of the Acts of the Apostles or their Epistles, how they have befouled them and gnawed them away, how they have defiled them in every kind of way, sometimes adding words which expressed their impious doctrine, sometimes taking out the opposing truths, will understand it most fully if he will read the books of Tertullian written against Marcion. It is no great thing that they should have corrupted the writings of Origen when they have dared to corrupt the sayings of God our Saviour. It is true that some persons may withhold their assent from what I am saying on the ground of the difference of the heresies; since it was one kind of heresy the partisans of which corrupted the Gospels, but it is another which is aimed at in these passages which, as we assert, have been inserted in the works of Origen. Let those who have such doubts consider that, as in all the saints dwells the one spirit of God (for the Apostle says, The spirits of the prophets are subject to the prophets, and again, We all have been made to drink of that one spirit); so also in all the heretics dwells the one spirit of the devil, who teaches them all and at all times the same or similar wickedness.
There may, however, be some to whom the instances we have given have less persuasive force because they have to do with Greek writers; and therefore, although it is a Greek writer for whom I am pleading, yet, since it is the Latin tongue which is, so to speak, entrusted with the argument, and they are Latin people before whom you have earnestly begged me to plead the cause of these men, and to show what wounds they suffer by the calumnious renderings of their works, it will be satisfactory to show that things of the same kind have happened to Latin as well as Greek writers, and that men approved for their saintly character have had a storm of calumny raised against them by the falsification of their works. I will recount things of still recent memory, so that nothing may be lacking to the manifest credibility of my contention, and its truth may lie open for all to see.
Hilary Bishop of Pictavium was a believer in the Catholic doctrine, and wrote a very complete work of instruction with the view of bringing back from their error those who had subscribed the faithless creed of Ariminum. This book fell into the hands of his adversaries and ill wishers, whether, as some said, by bribing his secretary, or by no matter what other cause. He knew nothing of this: but the book was so falsified by them, the saintly man being all the while entirely unconscious of it, that, when his enemies began to accuse him of heresy in the episcopal assembly, as holding what they knew they had corruptly inserted in his manuscript, he himself demanded the production of his book as evidence of his faith. It was brought from his house, and was found to be full of matter which he repudiated: but it caused him to be excommunicated and to be excluded from the meeting of the synod. In this case, however, though the crime was one of unexampled wickedness, the man who was the victim of it was alive, and present in the flesh; and the hostile faction could be convicted and brought to punishment, when their tricks became known and their machinations were exposed. A remedy was applied through statements, explanations, and similar things: for living men can take action on their own behalf, the dead can refute no accusations under which they labour.
Take another case. The whole collection of the letters of the martyr Cyprian is usually found in a single manuscript. Into this collection certain heretics who held a blasphemous doctrine about the Holy Spirit inserted a treatise of Tertullian on the Trinity, which was faultily expressed though he is himself an upholder of our faith: and from the copies thus made they wrote out a number of others; these they distributed through the whole of the vast city of Constantinople at a very low price: men were attracted by this cheapness and readily bought up the documents full of hidden snares of which they knew nothing; and thus the heretics found means of gaining credit for their impious doctrines through the authority of a great name. It happened, however, that, shortly after the publication, there were found there some of our catholic brothers who were able to expose this wicked fabrication, and recalled as many as they could reach from the entanglements of error. In this they partly succeeded. But there were a great many in those parts who remained convinced that the saintly martyr Cyprian held the belief which had been erroneously expressed by Tertullian.
I will add one other instance of the falsification of a document. It is one of recent memory, though it is an example of the primeval subtlety, and it surpasses all the stories of the ancients.
Source: Prefaces and Other Works (New Advent)