Around the end of the second century, Irenaeus, the bishop of Lyon in Gaul, complained about people he knew who claimed that the number of the beast should be 616 rather than 666. So far as Irenaeus was concerned, everyone who had met the author of the book of Revelation all knew firsthand that 666 was originally what was meant, and that the authentic tradition had been handed down through the true Church throughout the centuries. And besides (Irenaeus went on to say), doesn't it make more sense for the number of hundreds, tens, and ones to be equal to one another? And doesn't it have a kind of pleasing symmetry to note that the "real" number of the beast, 666, is only a deformed and incomplete version of Christ's number, that is to say 777?

"I do not know how it is that some have erred," Irenaeus sighed, "and have vitiated the middle number in the name, deducting the amount of fifty from it, so that instead of six decads they will have it that there is but one." (Adversus Haereses 5.30). He concluded that the 616 reading must have come about when some careless scribe copied the number down wrong when working on a manuscript. Evidently the error was repeated through ignorance or malice down until Irenaeus' own day.

But what if the number of the beast really is 616?

This question has resurfaced over the past few years. In the late 1990s, a group of papyrus fragments of the book of Revelation were found among the Oxyrhynchus Papyri, the stash of ancient documents first discovered in Egypt by Bernard Grenfell and Arthur Hunt at the end of the nineteenth century, and which is still being catalogued and compiled today. A couple of dozen scraps of papyrus, formerly classified under the generic name p115, were renamed POxy. 4499 and published in the 1999 volume of the Grenfell-Hunt series (number 66, as it happens!).

A number of things make POxy. 4499 interesting. First of all, it is one of the oldest extant manuscripts of the Book of Revelation, being palaeographically datable to the late third or early fourth century of the common era. Since Revelation was a very controversial book among ancient Christians, old copies of it are hard to find even in fragments.

But what is even more interesting is that a bit of Revelation 13:18 survives in this manuscript. The number of the Beast in that verse very clearly reads as χιϚ (chi iota stigma); that is to say, 600+10+6. All the other manuscripts we possess read χξϚ (chi xi stigma), or 600+60+6 -- the number since immortalized in countless heavy metal lyrics and horror movies. Will they all need to be rewritten?

Thanks to Irenaeus' complaint in Against Heresies, historians have known all along that both numbers were circulating among Christian churches in the second century. But which one is the original? Though POxy. 4499 is in very poor physical shape, the quality of the text is actually quite good, meaning that it was not originally a cheap or hastily-copied manuscript. This has led a number of prominent scholars to conclude that the reading in POxy. 4499 is a legitimately ancient one, and that it was therefore changed to 666 sometime around when Irenaeus was writing. Perhaps, as Irenaeus himself pointed out, people thought that 666 was more aesthetically pleasing. Or perhaps (if the common theory about the number referring to the emperor Nero is correct) people preferred the Hebraicized/Aramaicized form of the "beast"'s name to the Latinized one; the extra letter in the Hebrew form adds 50 to the final sum.

Anyway, though POxy. 4499 may be one of the oldest surviving manuscripts, it is still only a single manuscript. Its reading may not trump the rest of the Christian tradition just yet. So for the moment, all those death metal albums are safe. However, I would recommend against putting any Satanic numbers into your lyrics for a little while, just until we're sure.

Further Reading:

For a picture of the papyrus in question, see http://www.csad.ox.ac.uk/POxy/papyri/vol66/150dpi/pls7-8bk.jpg. The number you're looking for is in the fragment in the top left of the screen. It is at the end of the second full line of text, and it looks like an XIC with a line over it.

For a discussion of the significance of 616, see this discussion on the Oxford University web site: http://www.papyrology.ox.ac.uk/beast/numero.html.
For some reason, the authors completely dismiss the Nero theory, making something of a straw man out of what I think of as a good argument. I'm not sure why. But even so, the article is interesting and worth reading.