The first scholar to publicly question the letter's authenticity was Quentin Quesnell (1927–2012) in 1975. Quesnell's principal argument was that the actual manuscript had to be examined before it could be deemed authentic, and he suggested that it might be a modern hoax. He said that the publication of Otto Stählin's concordance of Clement in 1936, would make it possible to imitate Clement's style, which means that if it is a forgery, it would necessarily have been forged after 1936. On his last day of stay at the monastery, Smith found a catalogue from 1910 in which 191 books were listed, but not the Vossius book. Quesnell and others have argued that this fact supports the supposition that the book never was part of the Mar Saba library, but was brought there from outside, by for example Smith, with the text already inscribed. However, this has been contested. Smith found almost 500 books at his stay, so the list was far from complete and the silence from incomplete catalogues cannot be used as arguments against the existence of a book at the time the catalogue was made, Smith argued.