From the Latin of the Edition of Michael Lequien, as Given in Migne's Patrology.

After the rules of Christian dialectic and the review of the errors of ancient heresies comes at last the book "Concerning the Orthodox Faith." In this book, John of Damascus retains the same order as was adopted by Theodoret in his "Epitome of Divine Dogmas," but takes a different method. For the former, by the sheer weight of his own genius, framed various kinds of arguments against heretics, adducing the testimony of the sacred page, and thus he composed a concise treatise of Theology. Our author, however, did not confine himself to Scripture, but gathered together also the opinions of the holy Fathers, and produced a work marked with equal perspicuity and brevity, and forming an unexhausted storehouse of tradition in which nothing is to be found that has not been either sanctioned by the oecumenical synods or accepted by the approved leaders of the Church.

He followed, indeed, chiefly Gregory of Nazianzus, who, from the great accuracy of his erudition in divine matters, earned the title "The Theologian," and who has left scarcely any chapter of Christian learning untouched in his surviving works, and is free from any taint or suspicion of the slightest error. John had read his books with such assiduity that he seemed to hold them all in the embrace of his faithful memory. Wherefore throughout this work you may hear not so much John of Damascus as Gregory the Theologian expounding the mysteries of the orthodox faith. John further made use of Basil the great, of Gregory of Nyssa, and especially of Nemesius, bishop of Emesa in Syria, the most beloved of all; likewise of Cyril of Alexandria, Leo the Great, Leontius of Byzantium, the martyr Maximus: also of Athanasius, Chrysostom, Epiphanius, and, not to mention others, that writer who took the name of Dionysius the Areopagite. Out of all these he culled on every hand the flower of their opinions, and concocted most sweet honey of soundest doctrine. For his aim was, not to strike out views of his own or anything novel, but rather to collect into one single theological work the opinions of the ancients which were scattered through various volumes. And, indeed, in order that the reader may more readily perceive the method of this most careful teacher, we shall carefully note in the margin the names of the authors and of the books from which he copied each separate opinion.

To John of Damascus, therefore, belongs the merit of being the first to compose a volume packed with the sentences of catholic teachers. Accordingly his authority among theologians was always weighty, not only in the East but even in the West and with the Latins: all the more so after the translation into Latin of his book "Concerning the Orthodox Faith," by Burgundio, a citizen of Pisa, during the Pontificate of Eugenius the Third. Further it was this translation that was used by that master of sentences, St. Thomas, and other later theologians, down till the time when at the beginning of the 16th century Jacobus Faber Stapulensis attempted to produce a more perfect translation than was the old one with its uncouth and barbarous diction. But as this one, too, had many faults, Jacobus Billius, in the course of the same century, completed a version of greater elegance but yet lacking in carefulness and brevity. For, as Combefis remarked, "in translating the Damascene Billius shewed the rawness of a recruit." Combefis himself, however, considered the translation of Billy of no little worth; for when he was toiling at a new edition of the works of John of Damascus, he did not think it necessary to make a new translation once more, but was quite content to emend the earlier one. For he was rightly aware that all the most learned interpreters of lengthy tomes slip into many errors, and that it is much easier to improve on the errors of others than to detect one's own. Thus our translation will represent that of Billius purged of its blemishes and restored to a more concise style. but in order that our edition should go forth in a more accurate shape than the rest, besides using the older translations and various copies to the number of twenty or more codices, collated by my own hand, I have moreover revised the Greek phraseology and diction in those places of the Greek Fathers which the Damascene has massed together. Nay, further, omitting both the shorter commentaries of Faber on each chapter and also the longer ones of Judocus Clictoveus of Neoportua, neither of whom contributes much, if anything, to the intelligent understanding of the Greek Fathers, I have attempted by fuller annotations to place before the eyes of all a specimen of eastern theology, drawn alike from those teachers whom the Damascene copied and from Greeks of later date whom I had the privilege of consulting.

The customary division among the Latins of the work "Concerning the Orthodox Faith" into four books is found in no Greek codex, nor in the Greek edition of Verona. And, further, that division is not met with in the old manuscripts of the original Latin translation, except as a chance note written in ink by a second and later hand on the margins of some of them. Hence Marcus Hopperus appears to be mistaken in ascribing in the dedicatory epistle of the Græco-Latin edition of Basil the division into four books to the Latin translator: that is, unless I am mistaken, to Faber, whose edition he published. Traces of this, however, exist in the books of St. Thomas Aquinas. I therefore hold that this mode of division was devised and introduced by the Latins in imitation of the four books of "Sentences" of Peter Lombard. Codex Regius n.3445, and that is a very late one, alone seems to divide the "De Fide Orthodoxa" into two parts, the first, or peri tes Theologias, dealing indeed with the one triune God, the Creator and Provider, and the second, peri tes oikonomias, with God Incarnate, the Redeemer and Rewarder. But an objection to this division is the clear connection between chapter 43, in which the Incarnation, or "OEconomia Divina," is discussed, and the words which immediately precede it in the end of chapter 42, which is entitled "On Prædestination," making either chapter part of one continuous discussion. This fault cannot be taken to the other division into four parts. But in order not to startle the reader accustomed to the former division with too much novelty, I have, following Hopperus, assigned indeed to the Greek chapters the same numbers as were marked in the Greek codices, but I have not hesitated to divide the Latin translation into four books.

I have come across no edition of the old Latin translation; but the version of Jacobius Faber was issued in Paris by Judocus Clictoveus from the press of Henry Stephen in the year 1512, along with commentaries. Next, in the year 1535, Henry Pet, the printer of Basle, published the existing works of St. John of Damascus, and amongst them the four books "Concerning the Orthodox Faith, as translated by Jacobus Faber of Stapula," but without any commentary. After some years the same Henry in a second edition added the shorter commentaries of Clictoveus, and again in the edition published in the year 1537. In the preface to these editions there occurs among others the following sentence, "Now for the first time are added the annotations explaining all the difficulties and the hard and lofty passages." For a truth I know no older edition in which those explanations, such as they are, are given. Further, the author of these is asserted by Henricus Gravius, of the order of Preachers, in his own Latin edition of the works of holy John of Damascus, which he brought out at Cologne from the press of Peter Quentel, in the year 1546, to have been Jacobus Faber, and of a surety indeed in certain places, and in especial where the most holy mystery of the Eucharist is under discussion, the annotations are somewhat frigid in character and do not express with sufficient fulness the catholic faith. And this cannot be said without pain, for the sake of a man whom otherwise I should look up to as worthy of veneration, as almost one of my own house, had he not proved himself a traitor to his ancestral religion or at least somewhat too partial to innovators. As to the edition of our Gravius, learned as he was in both Latin and Greek, he revised the translation, Jacobus Faber's translation, and compared it with the Greek text and illustrated it with very short scholia, "for the sake of heretics," as he said in the dedicatory letter to Oswald, especially where they themselves try in vain to shake the doctrine of the Church as stated by the Damascene.

The book "Concerning the Orthodox Faith" Donatus Veronensis caused to be printed at Verona first in Greek only, and presented it to Clement the Seventh in the year 1531. Not till the year 1548 did he produce a version containing both the Greek and Latin, and again in the year 1575. Next, in the year 1577, Jacobus Billy published at Paris his own translation without the Greek text: and it was printed again in that same city in the years 1603 and 1617.

Here it will not be superfluous to call to mind that the great part of the first book, as they say, of the work "Concerning the Orthodox Faith" exists as the sixth volume of the works of Cyril of Alexandria, inscribed in that teacher's name, a result to be doubtless attributed to the carelessness of some copyist who found these writings of the Damascus along with others of Cyril.