We all know where priceless ancient manuscripts should be found: somewhere remote, preferably a desert, and we need a good hiding place; caves are perfect. In terms of creating a stereotype, the Dead Sea Scrolls are the model case, followed by the ancient Christian and Gnostic texts found at Nag Hammadi, in Egypt, around the same time. Yet one of the greatest such discoveries in modern times broke all those rules, which might explain why it remains so thoroughly unknown outside quite a narrow specialist world. And we still are only beginning to come to terms with the implications.The...