The reason I think that the new book by Panayiotis Tzamalikos (MSc, MPhil. PhD) will tip the scales in favor of the authenticity of the document is that his research goes back a century before John Moschus and explains why there were so many books of Clement at Mar Saba. It turns out that a community of 'Origenists' were established at Mar Saba from the very beginning and seemed to have included books of Clement in their library (all of which makes perfect sense given that Clement was Origen's teacher). Here is the blurb from Brill on this new book:
This is a critical analysis of texts included in Codex 573 (ninth century, Monastery of Metamorphosis, Meteora, Greece), which are published along with the present volume, in the same series. The Codex, entitled ‘The Book of Monk Cassian the Roman’, reveals a sixth-century heretofore unknown intellectual, namely, Cassian the Sabaite, native of Scythopolis, being its real author. By means of Medieval forgery, he has been eclipsed by a figment currently known as ‘John Cassian of Marseilles’, native of Scythia. Exploration reveals critical aspects of the interplay between Hellenism and Christianity, the Origenism and pseudo-Origenism of the sixth century, and Christian influence upon Neoplatonism in Late Antiquity. Cassian the Sabaite is probably the last great representative of a prolonged fruitful autumn of Late Antique Christian scholarship, who saw Hellenism as a treasured patrimony to draw on, rather than as a demon to be exorcised -which resulted in his ‘second death’(Rev. 2,11). Two edition volumes are now being published along with the present monograph. One, A Newly Discovered Greek Father, Cassian the Sabaite Eclipsed by John Cassian of Marseilles (folia 1r-118v). Two, An Ancient Commentary on the Book of Revelation: A Critical Edition of the Scholia in Apocalypsin. These Scholia were falsely attributed to Origen a century ago, but their real author is Cassian the Sabaite mainly drawing on a lost commentary on the Apocalypse by Didymus the Blind, as well as on Origen, Theodoret, Clement of Alexandria, Irenaeus, and others
The interesting idea which comes across in Tzamalikos's research is that the identification of these monks as 'Origenists' seems to be something a misnomer. They just happened to be highly educated monks and among their greatest flowers was a certain 'Cassian the Sabaite' who apparently wrote a number of texts falsely attributed to a number of other ancient writers. From Tzamalikos's web site:
The present volume, along with its sibling, A Newly Discovered Greek Father (Cassian the Sabaite eclipsed by ‘John Cassian’ of Marseilles), which is published simultaneously in the same series, is the result of research initially set out to determine the real author of the Scholia in Apocalypsin. These Scholia were discovered in 1908, in Codex 573 of the Monastery of Metamorphosis in Meteora, Greece, and Adolf von Harnack rushed into ascribing them to Origen, only four months after he saw them for the first time in July 1911. Never did this attribution enjoy unanimous acceptance by scholars ever since, hence this set of comments on part of John’s Apocalypse has remained an ‘orphan’ text, which made no mark in scholarship. My initial impression was that six months could suffice to determine their author, since meantime several scholars had come up with different opinions with respect to authorship. It took me three years, only in order to reach the mistaken conclusion that the author of the Scholia is Theodoret of Cyrrhus heavily drawing on a lost commentary on the Apocalypse by Didymus the Blind. Only after I was granted access to the Codex itself did Cassian the Sabaite come into the scene as a commanding figure who claims our attention, and as an immensely erudite author who deserves a fair hearing. Therefore, this monograph is an argument establishing the existence of Cassian the Sabaite as a first-class Christian intellectual, following the study and critical edition of his texts included in the same Codex. He is the author of a vast number of theological tracts currently classified as spuria, such as De Trinitate (Pseudo-Didymus), the Erotapokriseis by Pseudo-Caesarius, and several other pseudepigrapha.
We come across an unknown Greek Father, who was condemned to spiritual death and total extinction, only because inquisitors of doctrine deemed him as a sympathizer of Origen and an admirer of Didymus the Blind and of Evagrius; in other words, an author who drew on ‘heretics’ into his own writings. However, Cassian the Sabaite was in essence an Antiochene, who cherished the patrimony handed down by the great doctors of Antioch: Diodore of Tarsus, Theodore of Mopsuestia, Theodoret of Cyrrhus, and Nestorius to a certain extent. His association with all of these names, which emerges out of critical study of his texts, was sufficient reason for regarding him as a prime suspect of heresy.
The importance of pursuing this project has turned out to lie not simply in the discovery of certain unpublished texts. The real treasure of Codex 573 lies in what we learn about the turbulent times of Cassian of Sabaite. The sixth century controversy over what ‘Origenism’ really meant during those times comes up as an issue that receives further light. In addition, we come across a learned employment of the Aristotelian thought, which had been cultivated by the great schools of Edessa and Nisibis. Furthermore, it turns out that Classical and Late-Antique Greek patrimony were alive well into the sixth century, despite intolerant fanaticism by intellectuals of the imperial church and oppression by a crude despot like Justinian, who revelled in thinking of himself as a theologian.
The real value of Cassian the Sabaite is that he shakes part of our traditional knowledge, which we have been educated to take for granted. As a result, we realize that Theodoret was not the last great scholar of the early Christian era; Hellenism was not dead, not even moribund, at the time when Justinian closed down the Academy of Athens; what was styled ‘Origenism’ by that time, was a concoction by unlearned fanatic monks, who composed ‘anti-Origenistic’ documents and anathemas, which Justinian simply signed for the sake of his political aims and sanctioned as ‘edicts’ of his own.
These texts of Cassian the Sabaite treasure an abundant wealth of Greek as well as Christian learning and heritage. It is then only a supplementary conclusion that ‘John Cassian’, the alleged ‘father of Western monasticism’, is only a figment fabricated by means of extensive blatant Medieval forgery. As a result, Cassian, a native of Scythopolis, monk and presbyter, who died an abbot of the Great Laura of Sabas on 20 July 548, was condemned to utter obliteration as an intellectual and author. All of his writings were attributed to stars of Christian theology that were long dead, and are currently known as ‘spuria’ ascribed to either Athanasius, or Theodoret, or Justin, or Gregory of Nyssa, or Basil of Caesarea, or others. At the same time, his monastic texts were determined as the work by a phantasmal figure called ‘John Cassian’, allegedly a native of Scythia who lived in Marseilles.
The ninth-century Codex 573 of Metamorphosis (the Great Meteoron) is the sole extant set of documents that can reveal this canard. It survived the rage of men and the frenzy of centuries by being hidden in a vault, only to be discovered in 1908, along with another 610 codices that had remained concealed in that monastery for centuries, and their existence was unknown even to the monks themselves.
There are many voices coming out of the texts of Cassian that are included in this monument, which is as much a beautiful piece of art, as is it a meek and gentle record. The most humble, and yet most clear, of these voices is the one of Cassian the Sabaite himself, resounding the Classical and Late Antique Hellenism, along with a glorious tradition of Christian scholarship. He put to use both traditions during the dark period of 530s and 540s, and he did so vigorously and fruitfully, although it takes critical reading in order to realize that he applied his erudition in a clandestine manner. Now is the time to listen to this voice of Cassian the Sabaite, and allow him to advise us that, in some important respects, the sixth century was somewhat different from what it is currently thought.
As the reader can see there are a number of references to Clement of Alexandria in the writings of Cassian the Sabaite which could only have come from the library at Mar Saba. These references were made in the sixth century and compliment the witness of members of the circle of John Moschus there in both the late sixth and early seventh centuries and that of John of Damascus in the eighth century.
Morton Smith certainly became aware of John of Damascus's allusions to 'letters of Clement' at Mar Saba after his discovery of the Letter to Theodore. There is no evidence to suggest he knew of this reference before 1958. Yet even still, those who want to claim this discovery is a forgery typically ignore John's testimony as uncertain. Andrew Criddle has recently suggested at Stephen Carlson's website that John of Damascus might have meant to reference 'Clement of Rome' rather than 'Clement of Alexandria.' I don't see why this is necessary. No with the possible evidence of a library of writings of Clement at Mar Saba dating back to the sixth century, this seems even more unlikely. Now this argument can be effectively rejected and with it the likelihood that the Letter to Theodore was a remnant of a vast corpus of Clementine writings at Mar Saba seems highly likely.
Of course nothing will ever convince an established scholar to admit he was wrong so we shouldn't hold out hope for a change of mind on the part of the hoaxers. Nevertheless, this is the discovery which will tip the scales in favor of authenticity. Mark, my words ...