"The Nag Hammadi library consists of twelve books, plus eight leaves removed from a thirteenth book in late antiquity and tucked inside the front cover of the sixth. These eight leaves comprise a complete text [Trimorphic Protennoia], an independent treatise taken out of a book of collected essays." (NHL, 1988 edition, p.10)
... would have been the definitive word on the matter. Twelve books in the jar, not thirteen. In a scholarly paper, Robinson detailed the trace findings that led him to this conclusion. And yet otherwise-careful scholars - probably misled by the designation of TriProt as "Codex XIII" - continue to assert that the jar contained 13 books/codices. One of the most popular books on the subject - Elaine Pagels' The Gnostic Gospels - has this to say:
"[Muhammad 'Ali] ... raised his mattock, smashed the jar, and discovered inside thirteen papyrus books, bound in leather."
Pagels at least had the excuse of having published this book in 1979, when things were still up in the air a bit (the revisions to the 1977 edition of NHL to which she may or may not have had access are significant, though I don't know whether the above-quoted portion of Robinson's intro was among them.) But scholars writing much later are still making the same mistake. The other day, for example, I was perusing John Painter's 1997 book Just James, which is pretty careful scholarship throughout. Yet on page 159, one reads this:
"In the jar were thirteen codices ..."
What these false claims obscure is that the fact that there were 12 books in the jar and not 13 may be of some importance in getting inside the minds of those who packed the jar. Of course we don't know when in antiquity TriProt was torn out of another book and put into what we now know as Codex VI, but the possibility that it might have been done shortly prior to packing and sealing the jar is suggestive that the packers might have wanted to include TriProt, but did not want to put a 13th book in the jar. We know that the number 13 came to be considered unlucky by Christians at some point in time. Was it already so among that group at that point in time (say around 370)? Even if not, the number 12 would seem to have had a much greater symbolic significance to them, judging from the approving usages of that number in several tractates.
Mike Grondin, 10/13/2006