While telling us little about Jesus's actual marital status, this new fragment shows how religions create their own authorised history.

Our sources for the ancient past are often the merest shreds and patches, and peculiarly challenging is to trace the evolution of religions. Invariably, the process by which one particular orthodoxy succeeded in establishing itself as definitive was a complex and protracted one. Then, once cemented as canonical, back stories for it would come to be written, from which any lingering sense that the religion might once have been an inchoate swirl of competing doctrines and beliefs was effectively purged. The consequence is that histories told by believers about the early centuries of their own faith tend to serve as monuments to the obliteration as well as to the preservation of the past.

Hence the excitement this week surrounding the discovery of a tiny fragment of papyrus on which, for the first time in any ancient Christian manuscript, Jesus is recorded as speaking of 'my wife'. Although the provenance of this startling find is mysterious, its ultimate place of origin – presuming that it is not, as some scholars suspect, a forgery – can only have been Egypt.

This is not merely because the language of the fragment is Coptic. In Egypt, preserved in the dry and shifting sands of abandoned municipal tips, scraps of text that otherwise would have remained unknown have regularly been exhum.